billingcat is a small CRM and invoicing tool for freelancers and small businesses in a B2B context. Besides managing contacts, companies and notes, it can generate ZUGFeRD-compliant invoices (XML and PDF).
The project website is billingcat.de. The hosted version is currently in beta — registration is available on request via hallo@billingcat.de.
Note: billingcat is currently German only — both the source code comments and the user interface.
- Go with Echo
- GORM for database access
- Tailwind CSS and Alpine.js on the frontend
- SQLite by default, PostgreSQL optional
- speedata Publisher for PDF generation
git clone https://github.com/billingcat/crm.git
cd crm
cp config.toml.example config.toml
go run -tags sqlite .Then open http://localhost:5555/register. The first user to register becomes the admin.
For production deployment, PostgreSQL setup, mail configuration and PDF generation, see the manual at https://docs.billingcat.de/de/docs/install/ (German).
billingcat is part of a broader ecosystem of PDF, typesetting and publishing technologies.
billingcat is dual-licensed.
The open source version is released under the GNU Affero General Public License v3.0 (AGPL-3.0); see License.md. Running a modified version as a service means you have to publish your changes.
If that doesn't work for you — for example inside a proprietary product or a closed-source SaaS — a commercial license is available. Contact hallo@billingcat.de.
"billingcat" is a registered trademark of Patrick Gundlach. The name and the logo are not covered by the open source license, so forks and self-hosted instances should use their own branding.
Issues and pull requests are welcome.
See Notice.md for the third-party libraries used (Alpine.js, Tailwind CSS, Font Awesome and others).