diff --git a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/ApiRpcSyncer.kt b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/ApiRpcSyncer.kt
index f092deba..51dec12c 100644
--- a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/ApiRpcSyncer.kt
+++ b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/ApiRpcSyncer.kt
@@ -7,7 +7,7 @@ import io.horizontalsystems.ethereumkit.network.ConnectionManager
 import io.reactivex.Single
 import io.reactivex.disposables.CompositeDisposable
 import io.reactivex.schedulers.Schedulers
-import java.util.*
+import java.util.Timer
 import kotlin.concurrent.schedule
 
 class ApiRpcSyncer(
@@ -52,6 +52,14 @@ class ApiRpcSyncer(
         stopTimer()
     }
 
+    override fun pause() {
+        stopTimer()
+    }
+
+    override fun resume() {
+        startTimer()
+    }
+
     override fun <T: Any> single(rpc: JsonRpc<T>): Single<T> =
         rpcApiProvider.single(rpc)
     //endregion
@@ -69,6 +77,8 @@ class ApiRpcSyncer(
     }
 
     private fun startTimer() {
+        if (timer != null) return
+
         timer = Timer().apply {
             schedule(0, syncInterval * 1000) {
                 onFireTimer()
@@ -85,11 +95,9 @@ class ApiRpcSyncer(
         rpcApiProvider.single(BlockNumberJsonRpc())
                 .subscribeOn(Schedulers.io())
                 .observeOn(Schedulers.io())
-                .subscribe({ lastBlockNumber ->
+                .subscribe { lastBlockNumber ->
                     listener?.didUpdateLastBlockHeight(lastBlockNumber)
-                }, {
-                    state = SyncerState.NotReady(it)
-                }).let {
+                }.let {
                     disposables.add(it)
                 }
     }
diff --git a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/Interfaces.kt b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/Interfaces.kt
index fba99fde..6c1946b2 100644
--- a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/Interfaces.kt
+++ b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/Interfaces.kt
@@ -58,6 +58,8 @@ interface IRpcSyncer {
 
     fun start()
     fun stop()
+    fun pause()
+    fun resume()
     fun <T: Any> single(rpc: JsonRpc<T>): Single<T>
 }
 
diff --git a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/RpcBlockchain.kt b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/RpcBlockchain.kt
index dad3cc26..23b20296 100644
--- a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/RpcBlockchain.kt
+++ b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/RpcBlockchain.kt
@@ -133,6 +133,14 @@ class RpcBlockchain(
         syncer.stop()
     }
 
+    override fun pause() {
+        syncer.pause()
+    }
+
+    override fun resume() {
+        syncer.resume()
+    }
+
     override fun send(rawTransaction: RawTransaction, signature: Signature): Single<Transaction> {
         val transaction = transactionBuilder.transaction(rawTransaction, signature)
         val encoded = transactionBuilder.encode(rawTransaction, signature)
diff --git a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/WebSocketRpcSyncer.kt b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/WebSocketRpcSyncer.kt
index 5d8ec1d7..7f1af4fa 100644
--- a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/WebSocketRpcSyncer.kt
+++ b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/api/core/WebSocketRpcSyncer.kt
@@ -46,6 +46,10 @@ class WebSocketRpcSyncer(
         rpcSocket.stop()
     }
 
+    override fun pause() = Unit
+
+    override fun resume() = Unit
+
     override fun <T: Any> single(rpc: JsonRpc<T>): Single<T> {
         return Single.create { emitter ->
             send(
diff --git a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/core/EthereumKit.kt b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/core/EthereumKit.kt
index a5a58ca4..8ec0833f 100644
--- a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/core/EthereumKit.kt
+++ b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/core/EthereumKit.kt
@@ -148,6 +148,14 @@ class EthereumKit(
         connectionManager.stop()
     }
 
+    fun onEnterForeground() {
+        blockchain.resume()
+    }
+
+    fun onEnterBackground() {
+        blockchain.pause()
+    }
+
     fun refresh() {
         blockchain.refresh()
         transactionSyncManager.sync()
diff --git a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/core/Interfaces.kt b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/core/Interfaces.kt
index 04718d1c..43878ef4 100644
--- a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/core/Interfaces.kt
+++ b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/core/Interfaces.kt
@@ -53,6 +53,8 @@ interface IBlockchain {
     fun start()
     fun refresh()
     fun stop()
+    fun pause()
+    fun resume()
     fun syncAccountState()
 
     val syncState: EthereumKit.SyncState
diff --git a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/spv/core/SpvBlockchain.kt b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/spv/core/SpvBlockchain.kt
index 4a539516..e2a33a18 100644
--- a/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/spv/core/SpvBlockchain.kt
+++ b/ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/spv/core/SpvBlockchain.kt
@@ -13,7 +13,13 @@ import io.horizontalsystems.ethereumkit.core.IBlockchainListener
 import io.horizontalsystems.ethereumkit.core.ISpvStorage
 import io.horizontalsystems.ethereumkit.core.TransactionBuilder
 import io.horizontalsystems.ethereumkit.crypto.ECKey
-import io.horizontalsystems.ethereumkit.models.*
+import io.horizontalsystems.ethereumkit.models.Address
+import io.horizontalsystems.ethereumkit.models.DefaultBlockParameter
+import io.horizontalsystems.ethereumkit.models.GasPrice
+import io.horizontalsystems.ethereumkit.models.RawTransaction
+import io.horizontalsystems.ethereumkit.models.Signature
+import io.horizontalsystems.ethereumkit.models.Transaction
+import io.horizontalsystems.ethereumkit.models.TransactionLog
 import io.horizontalsystems.ethereumkit.network.INetwork
 import io.horizontalsystems.ethereumkit.spv.helpers.RandomHelper
 import io.horizontalsystems.ethereumkit.spv.models.AccountStateSpv
@@ -22,7 +28,11 @@ import io.horizontalsystems.ethereumkit.spv.net.BlockHelper
 import io.horizontalsystems.ethereumkit.spv.net.BlockValidator
 import io.horizontalsystems.ethereumkit.spv.net.PeerGroup
 import io.horizontalsystems.ethereumkit.spv.net.PeerProvider
-import io.horizontalsystems.ethereumkit.spv.net.handlers.*
+import io.horizontalsystems.ethereumkit.spv.net.handlers.AccountStateTaskHandler
+import io.horizontalsystems.ethereumkit.spv.net.handlers.AnnouncedBlockHandler
+import io.horizontalsystems.ethereumkit.spv.net.handlers.BlockHeadersTaskHandler
+import io.horizontalsystems.ethereumkit.spv.net.handlers.HandshakeTaskHandler
+import io.horizontalsystems.ethereumkit.spv.net.handlers.SendTransactionTaskHandler
 import io.horizontalsystems.ethereumkit.spv.net.tasks.HandshakeTask
 import io.reactivex.Single
 import io.reactivex.subjects.PublishSubject
@@ -61,6 +71,14 @@ class SpvBlockchain(
         TODO("not implemented")
     }
 
+    override fun pause() {
+        TODO("Not yet implemented")
+    }
+
+    override fun resume() {
+        TODO("Not yet implemented")
+    }
+
     override fun refresh() {
         TODO("not implemented")
     }