diff --git a/packages/ndk_flutter/android/build.gradle b/packages/ndk_flutter/android/build.gradle
index 26305fd27..6312bb6fd 100644
--- a/packages/ndk_flutter/android/build.gradle
+++ b/packages/ndk_flutter/android/build.gradle
@@ -1,6 +1,4 @@
-package android
-
-group = 'com.sebdeveloper6952.amberflutter.amberflutter'
+group = 'relaystr.ndk'
 version = '1.0-SNAPSHOT'
 
 buildscript {
@@ -11,7 +9,7 @@ buildscript {
 
     dependencies {
         classpath 'com.android.tools.build:gradle:8.12.3'
-        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:2.1.0"
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:2.2.20"
     }
 }
 
@@ -27,7 +25,7 @@ apply plugin: 'kotlin-android'
 
 android {
     if (project.android.hasProperty("namespace")) {
-        namespace = 'relastr.ndk'
+        namespace = 'relaystr.ndk'
     }
 
     compileSdk = 36
diff --git a/packages/ndk_flutter/android/settings.gradle b/packages/ndk_flutter/android/settings.gradle
index cbdd0a405..aa877f0ab 100644
--- a/packages/ndk_flutter/android/settings.gradle
+++ b/packages/ndk_flutter/android/settings.gradle
@@ -1,7 +1,5 @@
-package android
-
 plugins {
     id 'org.gradle.toolchains.foojay-resolver-convention' version '0.10.0'
 }
 
-rootProject.name = 'amberflutter'
+rootProject.name = 'ndk_flutter'
diff --git a/packages/ndk_flutter/android/src/main/AndroidManifest.xml b/packages/ndk_flutter/android/src/main/AndroidManifest.xml
index a2f47b605..44bda0c13 100644
--- a/packages/ndk_flutter/android/src/main/AndroidManifest.xml
+++ b/packages/ndk_flutter/android/src/main/AndroidManifest.xml
@@ -1,2 +1,10 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- Required on Android 11+ to detect and launch a NIP-55 external signer
+         (Amber, Primal, Aegis, ...) via the nostrsigner: scheme. -->
+    <queries>
+        <intent>
+            <action android:name="android.intent.action.VIEW" />
+            <data android:scheme="nostrsigner" />
+        </intent>
+    </queries>
 </manifest>
diff --git a/packages/ndk_flutter/android/src/main/kotlin/relaystr/ndk/DartNdkPlugin.kt b/packages/ndk_flutter/android/src/main/kotlin/relaystr/ndk/DartNdkPlugin.kt
index fb8ff76c2..45edafc76 100644
--- a/packages/ndk_flutter/android/src/main/kotlin/relaystr/ndk/DartNdkPlugin.kt
+++ b/packages/ndk_flutter/android/src/main/kotlin/relaystr/ndk/DartNdkPlugin.kt
@@ -1,13 +1,13 @@
 package relaystr.ndk
 
 import android.app.Activity
+import android.content.ContentResolver
+import android.content.Context
 import android.content.Intent
 import android.net.Uri
+import android.os.Handler
+import android.os.Looper
 import android.util.Log
-import androidx.annotation.NonNull
-import com.google.gson.Gson
-import android.content.Context
-
 
 import io.flutter.embedding.engine.plugins.FlutterPlugin
 import io.flutter.plugin.common.MethodCall
@@ -19,6 +19,13 @@ import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding
 import io.flutter.plugin.common.PluginRegistry
 
 
+/// ndk_flutter native plugin.
+///
+/// Hosts the NIP-55 "Android Signer Application" bridge (external signer apps
+/// such as Amber, Primal, Aegis, ...). Communication happens either silently
+/// through a ContentResolver query (when the user has pre-authorized the
+/// permission) or, as a fallback, by launching the signer via an Intent and
+/// reading the result in [onActivityResult].
 class DartNdkPlugin : FlutterPlugin, MethodCallHandler, ActivityAware,
     PluginRegistry.ActivityResultListener {
     private lateinit var _channel : MethodChannel
@@ -29,29 +36,135 @@ class DartNdkPlugin : FlutterPlugin, MethodCallHandler, ActivityAware,
     private val _intentRequestCode = 0
 
 
-
     override fun onAttachedToEngine(flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
         _channel = MethodChannel(flutterPluginBinding.binaryMessenger, "ndk")
         _channel.setMethodCallHandler(this)
         _context = flutterPluginBinding.applicationContext
     }
-    override fun onMethodCall(call: MethodCall, result: Result) {
-        _result = result
 
+    private fun isPackageInstalled(context: Context, target: String): Boolean {
+        return context.packageManager.getInstalledApplications(0)
+            .find { info -> info.packageName == target } != null
+    }
+
+    private fun isExternalSignerInstalled(context: Context): Boolean {
+        val intent = Intent(Intent.ACTION_VIEW, Uri.parse("$nostrSignerScheme:"))
+        return context.packageManager.queryIntentActivities(intent, 0).isNotEmpty()
+    }
+
+    override fun onMethodCall(call: MethodCall, result: Result) {
         when (call.method) {
-            "example" -> {
-                Log.i("example", "example onMethodCall")
+            nostrSignerScheme -> {
+                _result = MethodResultWrapper(result)
+
+                val paramsMap = call.arguments as? HashMap<*, *>
+                if (paramsMap == null) {
+                    Log.d("onMethodCall", "paramsMap is null")
+                    return
+                }
+
+                val requestType = paramsMap[keyType] as? String ?: ""
+                val currentUser = paramsMap[keyCurrentUser] as? String ?: ""
+                val pubKey = paramsMap[keyPubKey] as? String
+                    ?: paramsMap["pubkey"] as? String
+                    ?: ""
+                val id = paramsMap[keyId] as? String ?: ""
+                val uriData = paramsMap[keyUriData] as? String ?: ""
+                val permissions = paramsMap[keyPermissions] as? String ?: ""
+                // Signer app package captured at login (Amber, Primal, ...).
+                // Empty for get_public_key / legacy accounts.
+                val signerPackage = paramsMap[keyPackage] as? String ?: ""
+
+                // First try the silent ContentResolver path (pre-authorized
+                // permissions). Only attempt it when we know which signer to
+                // query (a captured package): querying a foreign provider
+                // (e.g. Amber for a Primal account) returns wrong/empty data.
+                // get_public_key (login) is Intent-only per NIP-55.
+                if (requestType != "get_public_key" && signerPackage.isNotEmpty()) {
+                    val data = getDataFromContentResolver(
+                        requestType.uppercase(),
+                        arrayOf(uriData, pubKey, currentUser),
+                        _context.contentResolver,
+                        signerPackage,
+                    )
+                    if (!data.isNullOrEmpty()) {
+                        Log.d("onMethodCall", "content resolver got data")
+                        _result.success(data)
+                        return
+                    }
+                }
+
+                // Fallback: launch the signer app via Intent.
+                val intent = Intent(
+                    Intent.ACTION_VIEW,
+                    Uri.parse("$nostrSignerScheme:$uriData")
+                )
+                intent.putExtra(keyType, requestType)
+                intent.putExtra(keyCurrentUser, currentUser)
+                intent.putExtra(keyPubKey, pubKey)
+                intent.putExtra("pubkey", pubKey)
+                intent.putExtra(keyId, id)
+                intent.putExtra(keyPermissions, permissions)
+                // Target the captured signer directly (no app chooser). Empty
+                // for login, so the user can pick a signer the first time.
+                if (signerPackage.isNotEmpty()) {
+                    intent.setPackage(signerPackage)
+                    intent.putExtra(keyPackage, signerPackage)
+                }
+
+                try {
+                    _activity?.startActivityForResult(intent, _intentRequestCode)
+                } catch (e: Exception) {
+                    Log.d("onMethodCall", "startActivityForResult failed for '$signerPackage': ${e.message}")
+                    _result.success(HashMap<String, String?>())
+                }
+            }
+
+            "isAppInstalled" -> {
+                val paramsMap = call.arguments as? HashMap<*, *>
+                val packageName = paramsMap?.get("packageName") as? String
+                val isInstalled = if (packageName.isNullOrEmpty()) {
+                    isExternalSignerInstalled(_context)
+                } else {
+                    isPackageInstalled(_context, packageName)
+                }
+                result.success(isInstalled)
             }
 
             else -> {
                 result.notImplemented()
-                return
             }
         }
     }
 
     override fun onActivityResult(requestCode: Int, resultCode: Int, intent: Intent?): Boolean {
-        return false;
+        if (requestCode == _intentRequestCode) {
+            if (resultCode == Activity.RESULT_OK && intent != null) {
+                val dataMap: HashMap<String, String?> = HashMap()
+                if (intent.hasExtra(keyResult)) {
+                    val result = intent.getStringExtra(keyResult)
+                    dataMap[keyResult] = result
+                    // keep `signature` populated for backwards compatibility
+                    dataMap[keySignature] = result
+                }
+                if (intent.hasExtra(keySignature)) {
+                    dataMap[keySignature] = intent.getStringExtra(keySignature)
+                }
+                if (intent.hasExtra(keyPackage)) {
+                    dataMap[keyPackage] = intent.getStringExtra(keyPackage)
+                }
+                if (intent.hasExtra(keyId)) {
+                    dataMap[keyId] = intent.getStringExtra(keyId)
+                }
+                if (intent.hasExtra(keyEvent)) {
+                    dataMap[keyEvent] = intent.getStringExtra(keyEvent)
+                }
+
+                _result.success(dataMap)
+                return true
+            }
+        }
+        return false
     }
 
     override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
@@ -76,5 +189,86 @@ class DartNdkPlugin : FlutterPlugin, MethodCallHandler, ActivityAware,
         _activity = null
     }
 
+    /*
+      Content resolver path adapted from:
+      https://github.com/0xchat-app/nostr-dart/blob/main/android/src/main/kotlin/com/oxchat/nostrcore/ChatcorePlugin.kt
+     */
+    private fun getDataFromContentResolver(
+        type: String,
+        uriData: Array<out String>,
+        resolver: ContentResolver,
+        signerPackage: String,
+    ): HashMap<String, String?>? {
+        try {
+            resolver.query(
+                Uri.parse("content://${signerPackage}.$type"),
+                uriData,
+                null,
+                null,
+                null
+            ).use {
+                if (it == null) {
+                    Log.d("getDataFromResolver", "resolver query is NULL")
+                    return null
+                }
+                if (it.moveToFirst()) {
+                    // The signer reports it cannot answer silently (permission
+                    // not granted / user denied): fall back to the Intent so
+                    // the user can approve, instead of returning empty data.
+                    val rejectedIndex = it.getColumnIndex("rejected")
+                    if (rejectedIndex >= 0) {
+                        Log.d("getDataFromResolver", "request rejected -> fallback to intent")
+                        return null
+                    }
+
+                    val dataMap: HashMap<String, String?> = HashMap()
+                    val resultIndex = it.getColumnIndex("result")
+                    if (resultIndex >= 0) {
+                        val result = it.getString(resultIndex)
+                        dataMap["result"] = result
+                        dataMap["signature"] = result
+                    }
+                    val index = it.getColumnIndex("signature")
+                    if (index >= 0) {
+                        dataMap["signature"] = it.getString(index)
+                    }
+                    val indexJson = it.getColumnIndex("event")
+                    if (indexJson >= 0) {
+                        dataMap["event"] = it.getString(indexJson)
+                    }
+
+                    // Only short-circuit the Intent if we actually got a result;
+                    // an empty/absent result means the signer didn't answer.
+                    if (dataMap["signature"].isNullOrEmpty()) {
+                        Log.d("getDataFromResolver", "empty result -> fallback to intent")
+                        return null
+                    }
+                    return dataMap
+                }
+            }
+        } catch (e: Exception) {
+            Log.d("contentResolver", e.message ?: "unknown error")
+            return null
+        }
+        return null
+    }
+}
+
+
+private class MethodResultWrapper internal constructor(result: MethodChannel.Result) :
+    MethodChannel.Result {
+    private val methodResult: MethodChannel.Result = result
+    private val handler: Handler = Handler(Looper.getMainLooper())
+
+    override fun success(result: Any?) {
+        handler.post { methodResult.success(result) }
+    }
+
+    override fun error(errorCode: String, errorMessage: String?, errorDetails: Any?) {
+        handler.post { methodResult.error(errorCode, errorMessage, errorDetails) }
+    }
 
+    override fun notImplemented() {
+        handler.post { methodResult.notImplemented() }
+    }
 }
diff --git a/packages/ndk_flutter/android/src/main/kotlin/relaystr/ndk/Nip55Constants.kt b/packages/ndk_flutter/android/src/main/kotlin/relaystr/ndk/Nip55Constants.kt
new file mode 100644
index 000000000..5ab3ef5fb
--- /dev/null
+++ b/packages/ndk_flutter/android/src/main/kotlin/relaystr/ndk/Nip55Constants.kt
@@ -0,0 +1,19 @@
+package relaystr.ndk
+
+/// Constants for the NIP-55 "Android Signer Application" protocol.
+///
+/// NIP-55 is a protocol implemented by several external signer apps
+/// (Amber, Primal, Aegis, ...). The wire format below is generic.
+
+const val nostrSignerScheme = "nostrsigner"
+
+const val keyType = "type"
+const val keyCurrentUser = "current_user"
+const val keyUriData = "uri_data"
+const val keyPubKey = "pubKey"
+const val keyId = "id"
+const val keyPermissions = "permissions"
+const val keyResult = "result"
+const val keySignature = "signature"
+const val keyPackage = "package"
+const val keyEvent = "event"
diff --git a/packages/ndk_flutter/lib/data_layer/data_sources/amber_flutter.dart b/packages/ndk_flutter/lib/data_layer/data_sources/amber_flutter.dart
deleted file mode 100644
index 88d18d31d..000000000
--- a/packages/ndk_flutter/lib/data_layer/data_sources/amber_flutter.dart
+++ /dev/null
@@ -1,10 +0,0 @@
-import 'package:amberflutter/amberflutter.dart';
-
-/// amber DS
-class AmberFlutterDS {
-  /// the amber obj
-  final Amberflutter amber;
-
-  /// ...
-  AmberFlutterDS(this.amber);
-}
diff --git a/packages/ndk_flutter/lib/data_layer/data_sources/nip55_signer.dart b/packages/ndk_flutter/lib/data_layer/data_sources/nip55_signer.dart
new file mode 100644
index 000000000..be67eab09
--- /dev/null
+++ b/packages/ndk_flutter/lib/data_layer/data_sources/nip55_signer.dart
@@ -0,0 +1,218 @@
+import 'dart:convert';
+
+import 'package:flutter/services.dart';
+import 'package:ndk/ndk.dart';
+
+/// A permission that can be requested when logging in with a NIP-55 external
+/// signer, so the signer can pre-authorize silent (ContentResolver) responses.
+///
+/// See https://github.com/nostr-protocol/nips/blob/master/55.md
+class Nip55Permission {
+  const Nip55Permission({required this.type, this.kind});
+
+  /// The request type to authorize, e.g. `sign_event`, `nip04_encrypt`.
+  final String type;
+
+  /// Optional event kind, only relevant for `sign_event`.
+  final int? kind;
+
+  Map<String, dynamic> toJson() {
+    return {'type': type, if (kind != null) 'kind': kind};
+  }
+}
+
+/// Result of a NIP-55 login (`get_public_key`).
+class Nip55LoginResult {
+  const Nip55LoginResult({required this.pubkey, this.package});
+
+  /// The user's public key, in hex format.
+  final String pubkey;
+
+  /// The signer app package name (e.g. Amber, Primal), if the signer returned
+  /// it. Used to target the same signer for subsequent requests.
+  final String? package;
+}
+
+/// Dart bridge to a NIP-55 "Android Signer Application".
+///
+/// NIP-55 is a protocol implemented by several external signer apps
+/// (Amber, Primal, Aegis, ...). This class talks to whichever compatible
+/// signer is installed through the native `ndk` method channel
+/// ([DartNdkPlugin]).
+///
+/// Every method resolves to a `Map` that contains (at least) a `signature`
+/// key with the result, mirroring the historical `amberflutter` API.
+class Nip55Signer {
+  /// The method channel shared with the native [DartNdkPlugin].
+  static const MethodChannel _channel = MethodChannel('ndk');
+
+  /// Default permissions requested at login so common operations can be
+  /// answered silently (via ContentResolver) without reopening the signer.
+  static const List<Nip55Permission> defaultPermissions = [
+    Nip55Permission(type: 'sign_event'),
+    Nip55Permission(type: 'nip04_encrypt'),
+    Nip55Permission(type: 'nip04_decrypt'),
+    Nip55Permission(type: 'nip44_encrypt'),
+    Nip55Permission(type: 'nip44_decrypt'),
+  ];
+
+  /// The signer app package (e.g. Amber, Primal), captured at login. Used to
+  /// target the right signer for both the ContentResolver and the Intent.
+  /// When `null`, the native side lets Android route through a compatible
+  /// signer app.
+  final String? package;
+
+  const Nip55Signer({this.package});
+
+  /// Whether a NIP-55 compatible external signer is installed.
+  Future<bool> isAppInstalled() async {
+    final data = await _channel.invokeMethod<bool>('isAppInstalled');
+    return data ?? false;
+  }
+
+  /// Requests the user's public key (login). Optionally pre-authorizes
+  /// [permissions] so subsequent requests can be answered silently.
+  ///
+  /// Returns the raw signer response map. Most callers want
+  /// [getPublicKeyHex] instead.
+  Future<Map<dynamic, dynamic>> getPublicKey({
+    List<Nip55Permission>? permissions,
+  }) async {
+    final arguments = <String, dynamic>{
+      'type': 'get_public_key',
+      'uri_data': 'login',
+    };
+    if (permissions != null) {
+      arguments['permissions'] = jsonEncode(permissions);
+    }
+    return _invoke(arguments);
+  }
+
+  /// Requests the user's public key and returns it as a hex pubkey, or `null`
+  /// if the user rejected or no key was returned.
+  ///
+  /// NIP-55 returns the key in the `result` field, in hex format. Older
+  /// signers (and Amber legacy) may return an npub instead, so both are
+  /// accepted. See https://github.com/nostr-protocol/nips/blob/master/55.md
+  Future<String?> getPublicKeyHex({List<Nip55Permission>? permissions}) async {
+    return (await login(permissions: permissions))?.pubkey;
+  }
+
+  /// Logs in: requests the user's public key, pre-authorizing [permissions]
+  /// (defaults to [defaultPermissions]), and captures the signer app package.
+  /// Returns `null` if the user rejected or no key was returned.
+  Future<Nip55LoginResult?> login({List<Nip55Permission>? permissions}) async {
+    final response = await getPublicKey(
+      permissions: permissions ?? defaultPermissions,
+    );
+    final raw = (response['result'] ?? response['signature']) as String?;
+    if (raw == null || raw.isEmpty) return null;
+    final pubkey = raw.startsWith('npub') ? Nip19.decode(raw) : raw;
+    final pkg = response['package'] as String?;
+    return Nip55LoginResult(
+      pubkey: pubkey,
+      package: (pkg != null && pkg.isNotEmpty) ? pkg : null,
+    );
+  }
+
+  Future<Map<dynamic, dynamic>> signEvent({
+    required String currentUser,
+    required String eventJson,
+    String? id,
+  }) {
+    return _invoke({
+      'type': 'sign_event',
+      'current_user': currentUser,
+      'uri_data': eventJson,
+      'id': id,
+    });
+  }
+
+  Future<Map<dynamic, dynamic>> nip04Encrypt({
+    required String plaintext,
+    required String currentUser,
+    required String pubKey,
+    String? id,
+  }) {
+    return _invoke(
+      _encryptArgs('nip04_encrypt', plaintext, currentUser, pubKey, id),
+    );
+  }
+
+  Future<Map<dynamic, dynamic>> nip04Decrypt({
+    required String ciphertext,
+    required String currentUser,
+    required String pubKey,
+    String? id,
+  }) {
+    return _invoke(
+      _encryptArgs('nip04_decrypt', ciphertext, currentUser, pubKey, id),
+    );
+  }
+
+  Future<Map<dynamic, dynamic>> nip44Encrypt({
+    required String plaintext,
+    required String currentUser,
+    required String pubKey,
+    String? id,
+  }) {
+    return _invoke(
+      _encryptArgs('nip44_encrypt', plaintext, currentUser, pubKey, id),
+    );
+  }
+
+  Future<Map<dynamic, dynamic>> nip44Decrypt({
+    required String ciphertext,
+    required String currentUser,
+    required String pubKey,
+    String? id,
+  }) {
+    return _invoke(
+      _encryptArgs('nip44_decrypt', ciphertext, currentUser, pubKey, id),
+    );
+  }
+
+  Future<Map<dynamic, dynamic>> decryptZapEvent({
+    required String eventJson,
+    required String currentUser,
+    String? id,
+  }) {
+    return _invoke({
+      'type': 'decrypt_zap_event',
+      'uri_data': eventJson,
+      'current_user': currentUser,
+      'id': id,
+    });
+  }
+
+  Map<String, dynamic> _encryptArgs(
+    String type,
+    String uriData,
+    String currentUser,
+    String pubKey,
+    String? id,
+  ) {
+    return {
+      'type': type,
+      'uri_data': uriData,
+      'current_user': currentUser,
+      // both casings are sent to stay compatible with signer implementations
+      'pubKey': pubKey,
+      'pubkey': pubKey,
+      'id': id,
+    };
+  }
+
+  Future<Map<dynamic, dynamic>> _invoke(Map<String, dynamic> arguments) async {
+    // Target the signer captured at login (if any), so the request goes to the
+    // right app and can be answered silently via its ContentResolver.
+    if (package != null) {
+      arguments['package'] = package;
+    }
+    final data = await _channel.invokeMethod<Map<dynamic, dynamic>>(
+      'nostrsigner',
+      arguments,
+    );
+    return data ?? {};
+  }
+}
diff --git a/packages/ndk_flutter/lib/data_layer/repositories/signers/amber_event_signer.dart b/packages/ndk_flutter/lib/data_layer/repositories/signers/nip55_event_signer.dart
similarity index 74%
rename from packages/ndk_flutter/lib/data_layer/repositories/signers/amber_event_signer.dart
rename to packages/ndk_flutter/lib/data_layer/repositories/signers/nip55_event_signer.dart
index ad5295bd3..937d09762 100644
--- a/packages/ndk_flutter/lib/data_layer/repositories/signers/amber_event_signer.dart
+++ b/packages/ndk_flutter/lib/data_layer/repositories/signers/nip55_event_signer.dart
@@ -3,7 +3,7 @@ import 'dart:async';
 import 'package:ndk/ndk.dart';
 import 'package:rxdart/rxdart.dart';
 
-import '../../data_sources/amber_flutter.dart';
+import '../../data_sources/nip55_signer.dart';
 
 /// Internal class to track a pending request with its completer
 class _PendingRequestEntry {
@@ -12,11 +12,13 @@ class _PendingRequestEntry {
   _PendingRequestEntry(this.completer, this.request);
 }
 
-/// amber (external app) https://github.com/greenart7c3/Amber singer
-class AmberEventSigner
-    with ConcurrencyLimiterMixin
-    implements EventSigner {
-  final AmberFlutterDS amberFlutterDS;
+/// Event signer backed by a NIP-55 external signer application.
+///
+/// NIP-55 is a protocol implemented by several external signer apps
+/// (Amber, Primal, Aegis, ...). This signer delegates all cryptographic
+/// operations to whichever compatible signer is installed via [Nip55Signer].
+class Nip55EventSigner with ConcurrencyLimiterMixin implements EventSigner {
+  final Nip55Signer nip55Signer;
 
   final String publicKey;
 
@@ -29,31 +31,32 @@ class AmberEventSigner
   @override
   final int maxConcurrentRequests;
 
-  /// Default Amber concurrency. Lower this if you target a flow that
+  /// Default external-signer concurrency. Lower this if you target a flow that
   /// prompts the user via Android intents for every request.
   static const int defaultMaxConcurrentRequests = 100;
 
-  /// get a amber event signer
-  AmberEventSigner({
+  /// get a NIP-55 external signer
+  Nip55EventSigner({
     required this.publicKey,
-    required this.amberFlutterDS,
+    required this.nip55Signer,
     this.maxConcurrentRequests = defaultMaxConcurrentRequests,
-  }) : assert(maxConcurrentRequests > 0,
-            'maxConcurrentRequests must be > 0');
+  }) : assert(maxConcurrentRequests > 0, 'maxConcurrentRequests must be > 0');
 
-  String get _npub =>
-      publicKey.startsWith('npub') ? publicKey : Nip19.encodePubKey(publicKey);
+  /// NIP-55 expects pubkeys in hex format ("All pubkeys in this NIP are in hex
+  /// format"), so `current_user` is always sent as hex.
+  String get _currentUser =>
+      publicKey.startsWith('npub') ? Nip19.decode(publicKey) : publicKey;
 
   String _extractResult(Map<dynamic, dynamic> map) {
     final result = map['signature'] as String?;
     if (result == null || result.isEmpty) {
-      throw Exception('Empty result from Amber');
+      throw Exception('Empty result from external signer');
     }
     return result;
   }
 
   String _generateRequestId() {
-    return 'amber_${DateTime.now().millisecondsSinceEpoch}_${_requestCounter++}';
+    return 'nip55_${DateTime.now().millisecondsSinceEpoch}_${_requestCounter++}';
   }
 
   void _notifyPendingRequestsChange() {
@@ -90,15 +93,15 @@ class AmberEventSigner
     );
     _notifyPendingRequestsChange();
 
-    // Throttle the actual call to Amber; queued requests still appear in
+    // Throttle the actual call to the signer; queued requests still appear in
     // `pendingRequests` so the UI sees the full backlog. If the request was
-    // cancelled while queued, skip the Amber call entirely.
+    // cancelled while queued, skip the signer call entirely.
     runThrottled(() async {
-      if (!_pendingRequests.containsKey(requestId)) {
-        throw SignerRequestCancelledException(requestId);
-      }
-      return await operation();
-    })
+          if (!_pendingRequests.containsKey(requestId)) {
+            throw SignerRequestCancelledException(requestId);
+          }
+          return await operation();
+        })
         .then((result) {
           if (!completer.isCompleted) {
             completer.complete(result);
@@ -121,8 +124,8 @@ class AmberEventSigner
   @override
   Future<Nip01Event> sign(Nip01Event event) async {
     return _trackRequest(SignerMethod.signEvent, () async {
-      final map = await amberFlutterDS.amber.signEvent(
-        currentUser: _npub,
+      final map = await nip55Signer.signEvent(
+        currentUser: _currentUser,
         eventJson: Nip01EventModel.fromEntity(event).toJsonString(),
         id: event.id,
       );
@@ -140,9 +143,9 @@ class AmberEventSigner
     return _trackRequest(
       SignerMethod.nip04Decrypt,
       () async {
-        final map = await amberFlutterDS.amber.nip04Decrypt(
+        final map = await nip55Signer.nip04Decrypt(
           ciphertext: msg,
-          currentUser: _npub,
+          currentUser: _currentUser,
           pubKey: destPubKey,
           id: id,
         );
@@ -158,9 +161,9 @@ class AmberEventSigner
     return _trackRequest(
       SignerMethod.nip04Encrypt,
       () async {
-        final map = await amberFlutterDS.amber.nip04Encrypt(
+        final map = await nip55Signer.nip04Encrypt(
           plaintext: msg,
-          currentUser: _npub,
+          currentUser: _currentUser,
           pubKey: destPubKey,
           id: id,
         );
@@ -184,9 +187,9 @@ class AmberEventSigner
     return _trackRequest(
       SignerMethod.nip44Encrypt,
       () async {
-        final map = await amberFlutterDS.amber.nip44Encrypt(
+        final map = await nip55Signer.nip44Encrypt(
           plaintext: plaintext,
-          currentUser: _npub,
+          currentUser: _currentUser,
           pubKey: recipientPubKey,
         );
         return _extractResult(map);
@@ -204,9 +207,9 @@ class AmberEventSigner
     return _trackRequest(
       SignerMethod.nip44Decrypt,
       () async {
-        final map = await amberFlutterDS.amber.nip44Decrypt(
+        final map = await nip55Signer.nip44Decrypt(
           ciphertext: ciphertext,
-          currentUser: _npub,
+          currentUser: _currentUser,
           pubKey: senderPubKey,
         );
         return _extractResult(map);
diff --git a/packages/ndk_flutter/lib/l10n/app_de.arb b/packages/ndk_flutter/lib/l10n/app_de.arb
index c366fba14..7f6bcad28 100644
--- a/packages/ndk_flutter/lib/l10n/app_de.arb
+++ b/packages/ndk_flutter/lib/l10n/app_de.arb
@@ -29,7 +29,7 @@
     }
   },
   "showNostrConnectQrcode": "Nostr-Connect-QR-Code anzeigen",
-  "loginWithAmber": "Mit Amber anmelden",
+  "loginWithSignerApp": "Mit Signer-App anmelden",
   "nostrConnectUrl": "Nostr-Connect-URL",
   "copy": "Kopieren",
   "addAccount": "Konto hinzufügen",
diff --git a/packages/ndk_flutter/lib/l10n/app_en.arb b/packages/ndk_flutter/lib/l10n/app_en.arb
index 5c9b9bc40..13d2278c9 100644
--- a/packages/ndk_flutter/lib/l10n/app_en.arb
+++ b/packages/ndk_flutter/lib/l10n/app_en.arb
@@ -86,9 +86,9 @@
   "@showNostrConnectQrcode": {
     "description": "Button text to show nostr connect QR code"
   },
-  "loginWithAmber": "Login with amber",
-  "@loginWithAmber": {
-    "description": "Button text to login with Amber"
+  "loginWithSignerApp": "Login with signer app",
+  "@loginWithSignerApp": {
+    "description": "Button text to login with an external Nostr signer app"
   },
   "nostrConnectUrl": "Nostr connect URL",
   "@nostrConnectUrl": {
diff --git a/packages/ndk_flutter/lib/l10n/app_es.arb b/packages/ndk_flutter/lib/l10n/app_es.arb
index f07fab16c..17111b111 100644
--- a/packages/ndk_flutter/lib/l10n/app_es.arb
+++ b/packages/ndk_flutter/lib/l10n/app_es.arb
@@ -20,7 +20,7 @@
   "bunkerAuthentication": "Autenticación Bunker",
   "tapToOpen": "Toca para abrir: {url}",
   "showNostrConnectQrcode": "Mostrar código QR de nostr connect",
-  "loginWithAmber": "Iniciar sesión con Amber",
+  "loginWithSignerApp": "Iniciar sesión con app de firma",
   "nostrConnectUrl": "URL de conexión Nostr",
   "copy": "Copiar",
   "addAccount": "Añadir cuenta",
diff --git a/packages/ndk_flutter/lib/l10n/app_fi.arb b/packages/ndk_flutter/lib/l10n/app_fi.arb
index b83f118f7..977e290ec 100644
--- a/packages/ndk_flutter/lib/l10n/app_fi.arb
+++ b/packages/ndk_flutter/lib/l10n/app_fi.arb
@@ -29,7 +29,7 @@
     }
   },
   "showNostrConnectQrcode": "Näytä Nostr Connect -QR-koodi",
-  "loginWithAmber": "Kirjaudu Amberilla",
+  "loginWithSignerApp": "Kirjaudu allekirjoitussovelluksella",
   "nostrConnectUrl": "Nostr Connect -URL",
   "copy": "Kopioi",
   "addAccount": "Lisää tili",
diff --git a/packages/ndk_flutter/lib/l10n/app_fr.arb b/packages/ndk_flutter/lib/l10n/app_fr.arb
index 30c9eab98..ea41ab3f3 100644
--- a/packages/ndk_flutter/lib/l10n/app_fr.arb
+++ b/packages/ndk_flutter/lib/l10n/app_fr.arb
@@ -20,7 +20,7 @@
   "bunkerAuthentication": "Authentification Bunker",
   "tapToOpen": "Appuyez pour ouvrir: {url}",
   "showNostrConnectQrcode": "Afficher le code QR nostr connect",
-  "loginWithAmber": "Se connecter avec Amber",
+  "loginWithSignerApp": "Se connecter avec une app de signature",
   "nostrConnectUrl": "URL de connexion Nostr",
   "copy": "Copier",
   "addAccount": "Ajouter un compte",
diff --git a/packages/ndk_flutter/lib/l10n/app_it.arb b/packages/ndk_flutter/lib/l10n/app_it.arb
index d8fe82e2a..706ec9910 100644
--- a/packages/ndk_flutter/lib/l10n/app_it.arb
+++ b/packages/ndk_flutter/lib/l10n/app_it.arb
@@ -29,7 +29,7 @@
     }
   },
   "showNostrConnectQrcode": "Mostra QR code Nostr Connect",
-  "loginWithAmber": "Accedi con Amber",
+  "loginWithSignerApp": "Accedi con app di firma",
   "nostrConnectUrl": "URL Nostr Connect",
   "copy": "Copia",
   "addAccount": "Aggiungi account",
diff --git a/packages/ndk_flutter/lib/l10n/app_ja.arb b/packages/ndk_flutter/lib/l10n/app_ja.arb
index efbf7f105..68c4e8391 100644
--- a/packages/ndk_flutter/lib/l10n/app_ja.arb
+++ b/packages/ndk_flutter/lib/l10n/app_ja.arb
@@ -20,7 +20,7 @@
   "bunkerAuthentication": "バンカー認証",
   "tapToOpen": "タップして開く：{url}",
   "showNostrConnectQrcode": "nostr connect QRコードを表示",
-  "loginWithAmber": "Amberでログイン",
+  "loginWithSignerApp": "署名アプリでログイン",
   "nostrConnectUrl": "Nostr接続URL",
   "copy": "コピー",
   "addAccount": "アカウントを追加",
diff --git a/packages/ndk_flutter/lib/l10n/app_localizations.dart b/packages/ndk_flutter/lib/l10n/app_localizations.dart
index 14b432684..0f9236703 100644
--- a/packages/ndk_flutter/lib/l10n/app_localizations.dart
+++ b/packages/ndk_flutter/lib/l10n/app_localizations.dart
@@ -237,11 +237,11 @@ abstract class AppLocalizations {
   /// **'Show nostr connect qrcode'**
   String get showNostrConnectQrcode;
 
-  /// Button text to login with Amber
+  /// Button text to login with an external Nostr signer app
   ///
   /// In en, this message translates to:
-  /// **'Login with amber'**
-  String get loginWithAmber;
+  /// **'Login with signer app'**
+  String get loginWithSignerApp;
 
   /// Title for nostr connect URL dialog
   ///
diff --git a/packages/ndk_flutter/lib/l10n/app_localizations_de.dart b/packages/ndk_flutter/lib/l10n/app_localizations_de.dart
index a11e26516..ca770a131 100644
--- a/packages/ndk_flutter/lib/l10n/app_localizations_de.dart
+++ b/packages/ndk_flutter/lib/l10n/app_localizations_de.dart
@@ -71,7 +71,7 @@ class AppLocalizationsDe extends AppLocalizations {
   String get showNostrConnectQrcode => 'Nostr-Connect-QR-Code anzeigen';
 
   @override
-  String get loginWithAmber => 'Mit Amber anmelden';
+  String get loginWithSignerApp => 'Mit Signer-App anmelden';
 
   @override
   String get nostrConnectUrl => 'Nostr-Connect-URL';
diff --git a/packages/ndk_flutter/lib/l10n/app_localizations_en.dart b/packages/ndk_flutter/lib/l10n/app_localizations_en.dart
index 09e888f98..846b5037f 100644
--- a/packages/ndk_flutter/lib/l10n/app_localizations_en.dart
+++ b/packages/ndk_flutter/lib/l10n/app_localizations_en.dart
@@ -71,7 +71,7 @@ class AppLocalizationsEn extends AppLocalizations {
   String get showNostrConnectQrcode => 'Show nostr connect qrcode';
 
   @override
-  String get loginWithAmber => 'Login with amber';
+  String get loginWithSignerApp => 'Login with signer app';
 
   @override
   String get nostrConnectUrl => 'Nostr connect URL';
diff --git a/packages/ndk_flutter/lib/l10n/app_localizations_es.dart b/packages/ndk_flutter/lib/l10n/app_localizations_es.dart
index efd0b0846..3f7c7bf2c 100644
--- a/packages/ndk_flutter/lib/l10n/app_localizations_es.dart
+++ b/packages/ndk_flutter/lib/l10n/app_localizations_es.dart
@@ -71,7 +71,7 @@ class AppLocalizationsEs extends AppLocalizations {
   String get showNostrConnectQrcode => 'Mostrar código QR de nostr connect';
 
   @override
-  String get loginWithAmber => 'Iniciar sesión con Amber';
+  String get loginWithSignerApp => 'Iniciar sesión con app de firma';
 
   @override
   String get nostrConnectUrl => 'URL de conexión Nostr';
diff --git a/packages/ndk_flutter/lib/l10n/app_localizations_fi.dart b/packages/ndk_flutter/lib/l10n/app_localizations_fi.dart
index 2c5496f30..acb2e3941 100644
--- a/packages/ndk_flutter/lib/l10n/app_localizations_fi.dart
+++ b/packages/ndk_flutter/lib/l10n/app_localizations_fi.dart
@@ -71,7 +71,7 @@ class AppLocalizationsFi extends AppLocalizations {
   String get showNostrConnectQrcode => 'Näytä Nostr Connect -QR-koodi';
 
   @override
-  String get loginWithAmber => 'Kirjaudu Amberilla';
+  String get loginWithSignerApp => 'Kirjaudu allekirjoitussovelluksella';
 
   @override
   String get nostrConnectUrl => 'Nostr Connect -URL';
diff --git a/packages/ndk_flutter/lib/l10n/app_localizations_fr.dart b/packages/ndk_flutter/lib/l10n/app_localizations_fr.dart
index 8405372f4..05ee238e4 100644
--- a/packages/ndk_flutter/lib/l10n/app_localizations_fr.dart
+++ b/packages/ndk_flutter/lib/l10n/app_localizations_fr.dart
@@ -71,7 +71,7 @@ class AppLocalizationsFr extends AppLocalizations {
   String get showNostrConnectQrcode => 'Afficher le code QR nostr connect';
 
   @override
-  String get loginWithAmber => 'Se connecter avec Amber';
+  String get loginWithSignerApp => 'Se connecter avec une app de signature';
 
   @override
   String get nostrConnectUrl => 'URL de connexion Nostr';
diff --git a/packages/ndk_flutter/lib/l10n/app_localizations_it.dart b/packages/ndk_flutter/lib/l10n/app_localizations_it.dart
index 1a5d377fd..7429d18cb 100644
--- a/packages/ndk_flutter/lib/l10n/app_localizations_it.dart
+++ b/packages/ndk_flutter/lib/l10n/app_localizations_it.dart
@@ -71,7 +71,7 @@ class AppLocalizationsIt extends AppLocalizations {
   String get showNostrConnectQrcode => 'Mostra QR code Nostr Connect';
 
   @override
-  String get loginWithAmber => 'Accedi con Amber';
+  String get loginWithSignerApp => 'Accedi con app di firma';
 
   @override
   String get nostrConnectUrl => 'URL Nostr Connect';
diff --git a/packages/ndk_flutter/lib/l10n/app_localizations_ja.dart b/packages/ndk_flutter/lib/l10n/app_localizations_ja.dart
index 63dbfd7ad..e2c190737 100644
--- a/packages/ndk_flutter/lib/l10n/app_localizations_ja.dart
+++ b/packages/ndk_flutter/lib/l10n/app_localizations_ja.dart
@@ -71,7 +71,7 @@ class AppLocalizationsJa extends AppLocalizations {
   String get showNostrConnectQrcode => 'nostr connect QRコードを表示';
 
   @override
-  String get loginWithAmber => 'Amberでログイン';
+  String get loginWithSignerApp => '署名アプリでログイン';
 
   @override
   String get nostrConnectUrl => 'Nostr接続URL';
diff --git a/packages/ndk_flutter/lib/l10n/app_localizations_pl.dart b/packages/ndk_flutter/lib/l10n/app_localizations_pl.dart
index c7f4aa4ef..80b8685a8 100644
--- a/packages/ndk_flutter/lib/l10n/app_localizations_pl.dart
+++ b/packages/ndk_flutter/lib/l10n/app_localizations_pl.dart
@@ -71,7 +71,7 @@ class AppLocalizationsPl extends AppLocalizations {
   String get showNostrConnectQrcode => 'Pokaż kod QR Nostr Connect';
 
   @override
-  String get loginWithAmber => 'Zaloguj się przez Amber';
+  String get loginWithSignerApp => 'Zaloguj się przez aplikację podpisującą';
 
   @override
   String get nostrConnectUrl => 'URL Nostr Connect';
diff --git a/packages/ndk_flutter/lib/l10n/app_localizations_pt.dart b/packages/ndk_flutter/lib/l10n/app_localizations_pt.dart
index c4b73a7cc..eeb363e61 100644
--- a/packages/ndk_flutter/lib/l10n/app_localizations_pt.dart
+++ b/packages/ndk_flutter/lib/l10n/app_localizations_pt.dart
@@ -71,7 +71,7 @@ class AppLocalizationsPt extends AppLocalizations {
   String get showNostrConnectQrcode => 'Mostrar código QR do Nostr Connect';
 
   @override
-  String get loginWithAmber => 'Iniciar sessão com Amber';
+  String get loginWithSignerApp => 'Iniciar sessão com app de assinatura';
 
   @override
   String get nostrConnectUrl => 'URL de ligação Nostr';
@@ -1142,7 +1142,7 @@ class AppLocalizationsPtBr extends AppLocalizationsPt {
   String get showNostrConnectQrcode => 'Mostrar QR code de conexão Nostr';
 
   @override
-  String get loginWithAmber => 'Entrar com Amber';
+  String get loginWithSignerApp => 'Entrar com app de assinatura';
 
   @override
   String get nostrConnectUrl => 'URL de conexão Nostr';
diff --git a/packages/ndk_flutter/lib/l10n/app_localizations_ru.dart b/packages/ndk_flutter/lib/l10n/app_localizations_ru.dart
index 895c45771..9674a3ca4 100644
--- a/packages/ndk_flutter/lib/l10n/app_localizations_ru.dart
+++ b/packages/ndk_flutter/lib/l10n/app_localizations_ru.dart
@@ -71,7 +71,7 @@ class AppLocalizationsRu extends AppLocalizations {
   String get showNostrConnectQrcode => 'Показать QR-код nostr connect';
 
   @override
-  String get loginWithAmber => 'Войти через Amber';
+  String get loginWithSignerApp => 'Войти через приложение для подписи';
 
   @override
   String get nostrConnectUrl => 'URL подключения Nostr';
diff --git a/packages/ndk_flutter/lib/l10n/app_localizations_zh.dart b/packages/ndk_flutter/lib/l10n/app_localizations_zh.dart
index 2e4dc1aa8..3b8281867 100644
--- a/packages/ndk_flutter/lib/l10n/app_localizations_zh.dart
+++ b/packages/ndk_flutter/lib/l10n/app_localizations_zh.dart
@@ -71,7 +71,7 @@ class AppLocalizationsZh extends AppLocalizations {
   String get showNostrConnectQrcode => '显示 nostr connect 二维码';
 
   @override
-  String get loginWithAmber => '使用 Amber 登录';
+  String get loginWithSignerApp => '使用签名应用登录';
 
   @override
   String get nostrConnectUrl => 'Nostr 连接 URL';
diff --git a/packages/ndk_flutter/lib/l10n/app_pl.arb b/packages/ndk_flutter/lib/l10n/app_pl.arb
index 282d46136..88cb2ba3d 100644
--- a/packages/ndk_flutter/lib/l10n/app_pl.arb
+++ b/packages/ndk_flutter/lib/l10n/app_pl.arb
@@ -29,7 +29,7 @@
     }
   },
   "showNostrConnectQrcode": "Pokaż kod QR Nostr Connect",
-  "loginWithAmber": "Zaloguj się przez Amber",
+  "loginWithSignerApp": "Zaloguj się przez aplikację podpisującą",
   "nostrConnectUrl": "URL Nostr Connect",
   "copy": "Kopiuj",
   "addAccount": "Dodaj konto",
diff --git a/packages/ndk_flutter/lib/l10n/app_pt.arb b/packages/ndk_flutter/lib/l10n/app_pt.arb
index 9066de071..b14b61015 100644
--- a/packages/ndk_flutter/lib/l10n/app_pt.arb
+++ b/packages/ndk_flutter/lib/l10n/app_pt.arb
@@ -20,7 +20,7 @@
   "bunkerAuthentication": "Autenticação Bunker",
   "tapToOpen": "Toque para abrir: {url}",
   "showNostrConnectQrcode": "Mostrar código QR do Nostr Connect",
-  "loginWithAmber": "Iniciar sessão com Amber",
+  "loginWithSignerApp": "Iniciar sessão com app de assinatura",
   "nostrConnectUrl": "URL de ligação Nostr",
   "copy": "Copiar",
   "addAccount": "Adicionar conta",
diff --git a/packages/ndk_flutter/lib/l10n/app_pt_BR.arb b/packages/ndk_flutter/lib/l10n/app_pt_BR.arb
index 19f40afa9..345f48091 100644
--- a/packages/ndk_flutter/lib/l10n/app_pt_BR.arb
+++ b/packages/ndk_flutter/lib/l10n/app_pt_BR.arb
@@ -20,7 +20,7 @@
   "bunkerAuthentication": "Autenticação Bunker",
   "tapToOpen": "Toque para abrir: {url}",
   "showNostrConnectQrcode": "Mostrar QR code de conexão Nostr",
-  "loginWithAmber": "Entrar com Amber",
+  "loginWithSignerApp": "Entrar com app de assinatura",
   "nostrConnectUrl": "URL de conexão Nostr",
   "copy": "Copiar",
   "addAccount": "Adicionar conta",
diff --git a/packages/ndk_flutter/lib/l10n/app_ru.arb b/packages/ndk_flutter/lib/l10n/app_ru.arb
index a65b35999..bb983d907 100644
--- a/packages/ndk_flutter/lib/l10n/app_ru.arb
+++ b/packages/ndk_flutter/lib/l10n/app_ru.arb
@@ -20,7 +20,7 @@
   "bunkerAuthentication": "Аутентификация Bunker",
   "tapToOpen": "Нажмите, чтобы открыть: {url}",
   "showNostrConnectQrcode": "Показать QR-код nostr connect",
-  "loginWithAmber": "Войти через Amber",
+  "loginWithSignerApp": "Войти через приложение для подписи",
   "nostrConnectUrl": "URL подключения Nostr",
   "copy": "Копировать",
   "addAccount": "Добавить аккаунт",
diff --git a/packages/ndk_flutter/lib/l10n/app_zh.arb b/packages/ndk_flutter/lib/l10n/app_zh.arb
index 0568fb94b..9f61b3e24 100644
--- a/packages/ndk_flutter/lib/l10n/app_zh.arb
+++ b/packages/ndk_flutter/lib/l10n/app_zh.arb
@@ -20,7 +20,7 @@
   "bunkerAuthentication": "Bunker 身份验证",
   "tapToOpen": "点击打开：{url}",
   "showNostrConnectQrcode": "显示 nostr connect 二维码",
-  "loginWithAmber": "使用 Amber 登录",
+  "loginWithSignerApp": "使用签名应用登录",
   "nostrConnectUrl": "Nostr 连接 URL",
   "copy": "复制",
   "addAccount": "添加账户",
diff --git a/packages/ndk_flutter/lib/main/ndk_flutter.dart b/packages/ndk_flutter/lib/main/ndk_flutter.dart
index d7a93fb4b..5bb776f20 100644
--- a/packages/ndk_flutter/lib/main/ndk_flutter.dart
+++ b/packages/ndk_flutter/lib/main/ndk_flutter.dart
@@ -1,6 +1,5 @@
 import 'dart:convert';
 
-import 'package:amberflutter/amberflutter.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 import 'package:ndk/data_layer/repositories/signers/nip46_event_signer.dart';
@@ -13,8 +12,8 @@ import 'package:nip07_event_signer/nip07_event_signer.dart';
 import 'package:crypto/crypto.dart';
 import 'package:http/http.dart' as http;
 
-import '../data_layer/data_sources/amber_flutter.dart';
-import '../data_layer/repositories/signers/amber_event_signer.dart';
+import '../data_layer/data_sources/nip55_signer.dart';
+import '../data_layer/repositories/signers/nip55_event_signer.dart';
 
 class NdkFlutter {
   final Ndk ndk;
@@ -109,9 +108,16 @@ class NdkFlutter {
         continue;
       }
 
-      if (account.signer is AmberEventSigner) {
+      if (account.signer is Nip55EventSigner) {
+        // `signerSeed` holds the signer app package (Amber, Primal, ...) so
+        // silent signing keeps working after restart.
+        final signer = account.signer as Nip55EventSigner;
         accounts.accounts.add(
-          NostrAccount(kind: AccountKinds.amber, pubkey: account.pubkey),
+          NostrAccount(
+            kind: AccountKinds.nip55,
+            pubkey: account.pubkey,
+            signerSeed: signer.nip55Signer.package,
+          ),
         );
         continue;
       }
@@ -175,16 +181,15 @@ class NdkFlutter {
         continue;
       }
 
-      if (account.kind == AccountKinds.amber) {
-        final amber = Amberflutter();
-        final amberFlutterDS = AmberFlutterDS(amber);
-
+      if (account.kind == AccountKinds.nip55) {
         ndk.accounts.addAccount(
           pubkey: account.pubkey,
           type: AccountType.externalSigner,
-          signer: AmberEventSigner(
+          signer: Nip55EventSigner(
             publicKey: account.pubkey,
-            amberFlutterDS: amberFlutterDS,
+            // restore the signer app package captured at login (null for
+            // legacy accounts -> Android routes through a compatible signer).
+            nip55Signer: Nip55Signer(package: account.signerSeed),
           ),
         );
         continue;
@@ -236,6 +241,11 @@ class NdkFlutter {
 
     if (accounts.loggedAccount == null) return;
     if (!ndk.accounts.hasAccount(accounts.loggedAccount!)) return;
-    ndk.accounts.switchAccount(pubkey: accounts.loggedAccount!);
+    try {
+      ndk.accounts.switchAccount(pubkey: accounts.loggedAccount!);
+    } catch (_) {
+      // stored logged account could not be restored (e.g. stale/corrupted
+      // state); ignore rather than crash app startup.
+    }
   }
 }
diff --git a/packages/ndk_flutter/lib/models/accounts.dart b/packages/ndk_flutter/lib/models/accounts.dart
index edd7d0cc0..3e3d1ddfe 100644
--- a/packages/ndk_flutter/lib/models/accounts.dart
+++ b/packages/ndk_flutter/lib/models/accounts.dart
@@ -23,7 +23,7 @@ class NostrWidgetsAccounts {
   }
 }
 
-enum AccountKinds { nip07, amber, bunker, pubkey, privkey }
+enum AccountKinds { nip07, nip55, bunker, pubkey, privkey }
 
 class NostrAccount {
   AccountKinds kind;
@@ -41,9 +41,12 @@ class NostrAccount {
   }
 
   factory NostrAccount.fromJson(Map<String, dynamic> json) {
+    // Legacy: NIP-55 external-signer accounts were stored as 'amber' before
+    // the rename to the protocol-generic 'nip55'.
+    final kindName = json['kind'] == 'amber' ? 'nip55' : json['kind'];
     return NostrAccount(
       kind: AccountKinds.values.firstWhere(
-        (e) => e.toString().split('.').last == json['kind'],
+        (e) => e.toString().split('.').last == kindName,
       ),
       pubkey: json['pubkey'],
       signerSeed: json['signerSeed'],
diff --git a/packages/ndk_flutter/lib/ndk_flutter.dart b/packages/ndk_flutter/lib/ndk_flutter.dart
index 4b71738ad..ad7dea367 100644
--- a/packages/ndk_flutter/lib/ndk_flutter.dart
+++ b/packages/ndk_flutter/lib/ndk_flutter.dart
@@ -1,12 +1,11 @@
 export 'main/config.dart';
 export 'main/ndk_flutter.dart';
 export 'repositories/flutter_secure_storage_wallets_repo.dart';
-export 'data_layer/repositories/signers/amber_event_signer.dart';
-export 'data_layer/data_sources/amber_flutter.dart';
+export 'data_layer/repositories/signers/nip55_event_signer.dart';
+export 'data_layer/data_sources/nip55_signer.dart';
 export 'widgets/widgets.dart';
 export 'verifiers/ndk_event_verifier.dart';
 export 'verifiers/web_event_verifier.dart';
 export 'signers/web_event_signer.dart';
 export 'signers/ndk_event_signer.dart';
 export 'utils/nostr_kinds.dart';
-export 'package:amberflutter/amberflutter.dart';
diff --git a/packages/ndk_flutter/lib/ndk_platform_interface.dart b/packages/ndk_flutter/lib/ndk_platform_interface.dart
index 9f14f0c14..4edb82a10 100644
--- a/packages/ndk_flutter/lib/ndk_platform_interface.dart
+++ b/packages/ndk_flutter/lib/ndk_platform_interface.dart
@@ -3,7 +3,7 @@ import 'package:plugin_platform_interface/plugin_platform_interface.dart';
 import 'ndk_method_channel.dart';
 
 abstract class NdkPlatform extends PlatformInterface {
-  /// Constructs a AmberflutterPlatform.
+  /// Constructs a NdkPlatform.
   NdkPlatform() : super(token: _token);
 
   static final Object _token = Object();
diff --git a/packages/ndk_flutter/lib/widgets/login/login_controller.dart b/packages/ndk_flutter/lib/widgets/login/login_controller.dart
index 6ce88cea7..f50d3de28 100644
--- a/packages/ndk_flutter/lib/widgets/login/login_controller.dart
+++ b/packages/ndk_flutter/lib/widgets/login/login_controller.dart
@@ -1,4 +1,3 @@
-import 'package:amberflutter/amberflutter.dart';
 import 'package:flutter/material.dart';
 import 'package:ndk/ndk.dart';
 import 'package:ndk_flutter/ndk_flutter.dart';
@@ -40,10 +39,10 @@ class LoginController extends ChangeNotifier {
   bool isNostrConnectDialogOpen = false;
   List<ToastificationItem> challengeToasts = [];
 
-  bool _isWaitingForAmber = false;
-  bool get isWaitingForAmber => _isWaitingForAmber;
-  set isWaitingForAmber(bool value) {
-    _isWaitingForAmber = value;
+  bool _isWaitingForExternalSigner = false;
+  bool get isWaitingForExternalSigner => _isWaitingForExternalSigner;
+  set isWaitingForExternalSigner(bool value) {
+    _isWaitingForExternalSigner = value;
     notifyListeners();
   }
 
@@ -95,35 +94,39 @@ class LoginController extends ChangeNotifier {
     }
   }
 
-  Future<void> loginWithAmber() async {
-    isWaitingForAmber = true;
-
-    final amber = Amberflutter();
-
-    final isAmberInstalled = await amber.isAppInstalled();
-
-    if (!isAmberInstalled) {
-      launchUrl(Uri.parse('https://github.com/greenart7c3/Amber'));
-      return;
-    }
+  Future<void> loginWithExternalSigner() async {
+    isWaitingForExternalSigner = true;
+    try {
+      const signer = Nip55Signer();
 
-    final amberFlutterDS = AmberFlutterDS(amber);
+      final isInstalled = await signer.isAppInstalled();
 
-    final amberResponse = await amber.getPublicKey();
+      if (!isInstalled) {
+        isWaitingForExternalSigner = false;
+        launchUrl(Uri.parse('https://github.com/greenart7c3/Amber'));
+        return;
+      }
 
-    final npub = amberResponse['signature'];
-    final pubkey = Nip19.decode(npub);
+      final loginResult = await signer.login();
+      if (loginResult == null) {
+        isWaitingForExternalSigner = false;
+        return;
+      }
 
-    final amberSigner = AmberEventSigner(
-      publicKey: pubkey,
-      amberFlutterDS: amberFlutterDS,
-    );
+      final externalSigner = Nip55EventSigner(
+        publicKey: loginResult.pubkey,
+        // pin the signer captured at login so later requests can be silent
+        nip55Signer: Nip55Signer(package: loginResult.package),
+      );
 
-    ndk.accounts.loginExternalSigner(signer: amberSigner);
+      ndk.accounts.loginExternalSigner(signer: externalSigner);
 
-    isWaitingForAmber = false;
+      isWaitingForExternalSigner = false;
 
-    await loggedIn();
+      await loggedIn();
+    } finally {
+      isWaitingForExternalSigner = false;
+    }
   }
 
   Future<void> loggedIn() async {
diff --git a/packages/ndk_flutter/lib/widgets/login/n_login.dart b/packages/ndk_flutter/lib/widgets/login/n_login.dart
index 28e9b7b3b..e84e6162f 100644
--- a/packages/ndk_flutter/lib/widgets/login/n_login.dart
+++ b/packages/ndk_flutter/lib/widgets/login/n_login.dart
@@ -17,7 +17,7 @@ class NLogin extends StatefulWidget {
   final bool enableNsecLogin;
   final bool enableNip07Login;
   final bool enableBunkerLogin;
-  final bool enableAmberLogin;
+  final bool enableSignerAppLogin;
   final bool enablePubkeyLogin;
   final NostrConnect? nostrConnect;
   final String? nsecLabelText;
@@ -36,7 +36,7 @@ class NLogin extends StatefulWidget {
     this.enableNsecLogin = true,
     this.enableNip07Login = true,
     this.enableBunkerLogin = true,
-    this.enableAmberLogin = true,
+    this.enableSignerAppLogin = true,
     this.enablePubkeyLogin = true,
     this.nostrConnect,
     this.nsecLabelText,
@@ -250,14 +250,13 @@ class _NLoginState extends State<NLogin> {
       ),
     );
 
-    final amberView = Padding(
+    final signerAppView = Padding(
       padding: EdgeInsetsGeometry.only(bottom: bottomPadding),
-      child: FilledButton.icon(
-        onPressed: controller.isWaitingForAmber
+      child: FilledButton(
+        onPressed: controller.isWaitingForExternalSigner
             ? null
-            : controller.loginWithAmber,
-        label: Text(AppLocalizations.of(context)!.loginWithAmber),
-        icon: Icon(Icons.diamond),
+            : controller.loginWithExternalSigner,
+        child: Text(AppLocalizations.of(context)!.loginWithSignerApp),
       ),
     );
 
@@ -272,7 +271,7 @@ class _NLoginState extends State<NLogin> {
         if (widget.enableNip07Login && kIsWeb) nip07View,
         if (widget.enableBunkerLogin || widget.enableNostrConnectLogin)
           bunkerView,
-        if (widget.enableAmberLogin && isAndroid) amberView,
+        if (widget.enableSignerAppLogin && isAndroid) signerAppView,
         if (widget.enableAccountCreation) createAccountView,
       ],
     );
diff --git a/packages/ndk_flutter/lib/widgets/pending_requests/n_pending_requests.dart b/packages/ndk_flutter/lib/widgets/pending_requests/n_pending_requests.dart
index 252f20aaa..f20664a3c 100644
--- a/packages/ndk_flutter/lib/widgets/pending_requests/n_pending_requests.dart
+++ b/packages/ndk_flutter/lib/widgets/pending_requests/n_pending_requests.dart
@@ -7,7 +7,7 @@ import 'package:ndk_flutter/ndk_flutter.dart';
 /// State of the pending requests widget
 enum NPendingRequestsState { hidden, collapsed, expanded }
 
-/// A widget that displays pending signer requests (for Amber, bunker, extension).
+/// A widget that displays pending signer requests (for signer app, bunker, extension).
 ///
 /// This widget shows a floating panel at the bottom of the screen when there are
 /// pending requests waiting for user approval on external signers.
@@ -115,7 +115,7 @@ class _NPendingRequestsState extends State<NPendingRequests> {
     final signer = account.signer;
     final signerType = signer.runtimeType.toString();
 
-    if (signerType.contains('Amber')) return 'Amber';
+    if (signerType.contains('Nip55')) return 'signer app';
     if (signerType.contains('Nip46')) return 'bunker';
     if (signerType.contains('Nip07')) return 'extension';
 
diff --git a/packages/ndk_flutter/pubspec.yaml b/packages/ndk_flutter/pubspec.yaml
index a367cd310..f24f80e43 100644
--- a/packages/ndk_flutter/pubspec.yaml
+++ b/packages/ndk_flutter/pubspec.yaml
@@ -22,7 +22,6 @@ environment:
 resolution: workspace
 
 dependencies:
-  amberflutter: ^0.0.9
   android_intent_plus: ^6.0.0
   crypto: ">=3.0.0 <4.0.0"
   flutter:
@@ -50,5 +49,10 @@ dev_dependencies:
 
 flutter:
   generate: true
+  plugin:
+    platforms:
+      android:
+        package: relaystr.ndk
+        pluginClass: DartNdkPlugin
   assets:
     - assets/images/
diff --git a/packages/sample-app/README.md b/packages/sample-app/README.md
index 7bc23ff90..943586321 100644
--- a/packages/sample-app/README.md
+++ b/packages/sample-app/README.md
@@ -17,7 +17,8 @@ Main package: [🔗 Dart Nostr Development Kit (NDK)](https://pub.dev/packages/n
 
 4. start app `flutter run`
 
-## Amber
+## NIP-55 signer
 
-Amber is a external nostr signer. Its not required in order to run this application. \
-You can read more about it here: [https://github.com/greenart7c3/Amber](https://github.com/greenart7c3/Amber)
+A NIP-55 compatible external Nostr signer is optional for running this
+application. Amber is one app that implements NIP-55, but the sample app is not
+specific to Amber.
diff --git a/packages/sample-app/android/app/build.gradle b/packages/sample-app/android/app/build.gradle
index f55417ea9..a741026ec 100644
--- a/packages/sample-app/android/app/build.gradle
+++ b/packages/sample-app/android/app/build.gradle
@@ -33,8 +33,8 @@ if (flutterVersionName == null) {
 
 android {
     namespace "com.example.example"
-    compileSdkVersion 35
-    ndkVersion "27.0.12077973"
+    compileSdk = 36
+    ndkVersion "28.2.13676358"
 
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_17
diff --git a/packages/sample-app/android/build.gradle b/packages/sample-app/android/build.gradle
index 8b7b3622e..f2d7ed74c 100644
--- a/packages/sample-app/android/build.gradle
+++ b/packages/sample-app/android/build.gradle
@@ -1,5 +1,5 @@
 buildscript {
-    ext.kotlin_version = '2.1.0'
+    ext.kotlin_version = '2.2.20'
     repositories {
         google()
         mavenCentral()
@@ -21,7 +21,7 @@ subprojects {
     afterEvaluate { project ->
         if (project.hasProperty('android')) {
             project.android {
-                compileSdkVersion 35
+                compileSdkVersion 36
             }
         }
     }
diff --git a/packages/sample-app/android/gradle.properties b/packages/sample-app/android/gradle.properties
index 598d13fee..f2122b21a 100644
--- a/packages/sample-app/android/gradle.properties
+++ b/packages/sample-app/android/gradle.properties
@@ -1,3 +1,7 @@
 org.gradle.jvmargs=-Xmx4G
 android.useAndroidX=true
 android.enableJetifier=true
+# This builtInKotlin flag was added automatically by Flutter migrator
+android.builtInKotlin=false
+# This newDsl flag was added automatically by Flutter migrator
+android.newDsl=false
diff --git a/packages/sample-app/android/gradle/wrapper/gradle-wrapper.properties b/packages/sample-app/android/gradle/wrapper/gradle-wrapper.properties
index afa1e8eb0..e4ef43fb9 100644
--- a/packages/sample-app/android/gradle/wrapper/gradle-wrapper.properties
+++ b/packages/sample-app/android/gradle/wrapper/gradle-wrapper.properties
@@ -2,4 +2,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.10.2-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.14-all.zip
diff --git a/packages/sample-app/android/settings.gradle b/packages/sample-app/android/settings.gradle
index 220471060..0e4b36226 100644
--- a/packages/sample-app/android/settings.gradle
+++ b/packages/sample-app/android/settings.gradle
@@ -23,8 +23,8 @@ pluginManagement {
 
 plugins {
     id "dev.flutter.flutter-plugin-loader" version "1.0.0"
-    id "com.android.application" version "8.7.1" apply false
-    id "org.jetbrains.kotlin.android" version "2.1.0" apply false
+    id "com.android.application" version "8.11.1" apply false
+    id "org.jetbrains.kotlin.android" version "2.2.20" apply false
 }
 
 include ":app"
diff --git a/packages/sample-app/lib/main.dart b/packages/sample-app/lib/main.dart
index f99d3c575..d75cc6d23 100644
--- a/packages/sample-app/lib/main.dart
+++ b/packages/sample-app/lib/main.dart
@@ -16,7 +16,7 @@ import 'package:protocol_handler/protocol_handler.dart';
 
 import 'demo_app_config.dart';
 
-bool amberAvailable = false;
+bool signerAppAvailable = false;
 
 late Ndk ndk;
 final ndkFlutter = NdkFlutter(ndk: ndk);
@@ -32,10 +32,10 @@ Future<void> main() async {
   }
 
   try {
-    final amber = Amberflutter();
-    amberAvailable = await amber.isAppInstalled();
+    const signer = Nip55Signer();
+    signerAppAvailable = await signer.isAppInstalled();
   } catch (e) {
-    // not on android or amber not installed
+    // not on android or no signer app installed
   }
 
   final cacheManager = kIsWeb
diff --git a/packages/sample-app/lib/amber_page.dart b/packages/sample-app/lib/nip55_signer_page.dart
similarity index 84%
rename from packages/sample-app/lib/amber_page.dart
rename to packages/sample-app/lib/nip55_signer_page.dart
index badf2258a..ea9013200 100644
--- a/packages/sample-app/lib/amber_page.dart
+++ b/packages/sample-app/lib/nip55_signer_page.dart
@@ -1,22 +1,22 @@
 import 'dart:convert';
 
-import 'package:amberflutter/amberflutter.dart';
 import 'package:flutter/material.dart';
 import 'package:ndk/ndk.dart';
+import 'package:ndk_flutter/ndk_flutter.dart';
 
-class AmberPage extends StatefulWidget {
-  const AmberPage({super.key});
+class Nip55SignerPage extends StatefulWidget {
+  const Nip55SignerPage({super.key});
 
   @override
-  State<AmberPage> createState() => _AmberPageState();
+  State<Nip55SignerPage> createState() => _Nip55SignerPageState();
 }
 
-class _AmberPageState extends State<AmberPage> {
+class _Nip55SignerPageState extends State<Nip55SignerPage> {
   String _npub = '';
   String _pubkeyHex = '';
   String _text = '';
   String _cipherText = '';
-  final amber = Amberflutter();
+  final nip55Signer = const Nip55Signer();
 
   @override
   Widget build(BuildContext context) {
@@ -25,12 +25,12 @@ class _AmberPageState extends State<AmberPage> {
       children: <Widget>[
         FilledButton(
           onPressed: () async {
-            amber.getPublicKey(
+            nip55Signer.getPublicKey(
               permissions: [
-                const Permission(
+                const Nip55Permission(
                   type: "nip04_encrypt",
                 ),
-                const Permission(
+                const Nip55Permission(
                   type: "nip04_decrypt",
                 ),
               ],
@@ -50,14 +50,14 @@ class _AmberPageState extends State<AmberPage> {
               'id': '',
               'pubkey': Nip19.decode(_npub),
               'kind': 1,
-              'content': 'Hello from Amber Flutter!',
+              'content': 'Hello from NDK Flutter!',
               'created_at':
                   (DateTime.now().millisecondsSinceEpoch / 1000).round(),
               'tags': [],
               'sig': '',
             });
 
-            amber
+            nip55Signer
                 .signEvent(
               currentUser: _npub,
               eventJson: eventJson,
@@ -76,14 +76,14 @@ class _AmberPageState extends State<AmberPage> {
               'id': '',
               'pubkey': Nip19.decode(_npub),
               'kind': 1,
-              'content': 'Hello from Amber Flutter!',
+              'content': 'Hello from NDK Flutter!',
               'created_at':
                   (DateTime.now().millisecondsSinceEpoch / 1000).round(),
               'tags': [],
               'sig': '',
             });
 
-            var value = await amber.signEvent(
+            var value = await nip55Signer.signEvent(
               currentUser: _npub,
               eventJson: eventJson,
             );
@@ -100,9 +100,9 @@ class _AmberPageState extends State<AmberPage> {
         ),
         FilledButton(
           onPressed: () {
-            amber
+            nip55Signer
                 .nip04Encrypt(
-              plaintext: "Hello from Amber Flutter, Nip 04!",
+              plaintext: "Hello from NDK Flutter, Nip 04!",
               currentUser: _npub,
               pubKey: _pubkeyHex,
             )
@@ -117,7 +117,7 @@ class _AmberPageState extends State<AmberPage> {
         ),
         FilledButton(
           onPressed: () async {
-            amber
+            nip55Signer
                 .nip04Decrypt(
               ciphertext: _cipherText,
               currentUser: _npub,
@@ -129,7 +129,7 @@ class _AmberPageState extends State<AmberPage> {
               });
             });
             // ;
-            amber
+            nip55Signer
                 .nip04Decrypt(
               ciphertext: _cipherText,
               currentUser: _npub,
@@ -141,7 +141,7 @@ class _AmberPageState extends State<AmberPage> {
               });
             });
             //   ,
-            amber
+            nip55Signer
                 .nip04Decrypt(
               ciphertext: _cipherText,
               currentUser: _npub,
@@ -157,9 +157,9 @@ class _AmberPageState extends State<AmberPage> {
         ),
         FilledButton(
           onPressed: () {
-            amber
+            nip55Signer
                 .nip44Encrypt(
-              plaintext: "Hello from Amber Flutter, Nip 44!",
+              plaintext: "Hello from NDK Flutter, Nip 44!",
               currentUser: _npub,
               pubKey: _pubkeyHex,
             )
@@ -174,7 +174,7 @@ class _AmberPageState extends State<AmberPage> {
         ),
         FilledButton(
           onPressed: () {
-            amber
+            nip55Signer
                 .nip44Decrypt(
               ciphertext: _cipherText,
               currentUser: _npub,
diff --git a/packages/sample-app/lib/widgets_demo_page.dart b/packages/sample-app/lib/widgets_demo_page.dart
index 12dab5a0d..8aa794b5b 100644
--- a/packages/sample-app/lib/widgets_demo_page.dart
+++ b/packages/sample-app/lib/widgets_demo_page.dart
@@ -215,7 +215,7 @@ class _WidgetsDemoPageState extends State<WidgetsDemoPage> {
                             setState(() => _showLogin = false);
                           },
                           enableNip07Login: false,
-                          enableAmberLogin: false,
+                          enableSignerAppLogin: false,
                           nostrConnect: NostrConnect(
                             appName: 'NDK sample app',
                             relays: [
diff --git a/packages/sample-app/pubspec.lock b/packages/sample-app/pubspec.lock
index 145170021..ffe22d91d 100644
--- a/packages/sample-app/pubspec.lock
+++ b/packages/sample-app/pubspec.lock
@@ -1,14 +1,6 @@
 # Generated by pub
 # See https://dart.dev/tools/pub/glossary#lockfile
 packages:
-  amberflutter:
-    dependency: "direct main"
-    description:
-      name: amberflutter
-      sha256: "5101b36419a93e0620a227ada25690286efc93ab9de59dc80e7c3a0c29ccd348"
-      url: "https://pub.dev"
-    source: hosted
-    version: "0.0.9"
   android_intent_plus:
     dependency: transitive
     description:
@@ -587,7 +579,7 @@ packages:
       path: "../ndk"
       relative: true
     source: path
-    version: "0.8.4-dev.1"
+    version: "0.8.4-dev.2"
   ndk_bip32_keys:
     dependency: transitive
     description:
@@ -602,14 +594,14 @@ packages:
       path: "../drift"
       relative: true
     source: path
-    version: "0.1.1-dev.1"
+    version: "0.1.1-dev.3"
   ndk_flutter:
     dependency: "direct main"
     description:
       path: "../ndk_flutter"
       relative: true
     source: path
-    version: "0.8.4-dev.1"
+    version: "0.8.4-dev.3"
   nested:
     dependency: transitive
     description:
@@ -624,7 +616,7 @@ packages:
       path: "../nip07_event_signer"
       relative: true
     source: path
-    version: "1.1.0-dev.1"
+    version: "1.1.0-dev.2"
   objective_c:
     dependency: transitive
     description:
diff --git a/packages/sample-app/pubspec.yaml b/packages/sample-app/pubspec.yaml
index 0692ed068..e28387bba 100644
--- a/packages/sample-app/pubspec.yaml
+++ b/packages/sample-app/pubspec.yaml
@@ -52,7 +52,6 @@ dependencies:
   protocol_handler: ^0.2.0
   http: ^1.2.0
   qr_flutter: ^4.1.0
-  amberflutter: any
 
 dev_dependencies:
   flutter_test: