crm

billingcat

billingcat is a lightweight CRM and invoicing tool, made for freelancers and small businesses. It helps you manage contacts, companies and notes – but its main focus is on invoicing in a b2b environment. You can even generate ZUGFeRD-compliant invoices (both XML and PDF).

Check out billingcat.de – you can sign up for the newsletter there to get notified once the public alpha SaaS goes live!

Features

• Create and download ZUGFeRD invoices (XML + PDF)
• Simple but complete CRM for contacts, companies and notes
• Focused on invoice management
• Designed for freelancers and small businesses
• Open Source and SaaS

Note: billingcat is currently available only in German (source code and user interface). "billingcat" is a registered trademark of Patrick Gundlach.

Tech stack

• Go + Echo for the backend
• GORM as ORM
• Tailwind CSS + Alpine.js for the frontend
• SQLite as the default database (built-in, file-based, zero-config)
• PostgreSQL as an alternative database
• speedata Publisher for PDF generation

Installation

billingcat can be self-hosted or used as a hosted SaaS on billingcat.de.

The recommended and up-to-date installation instructions are documented in the billingcat manual (currently German only):

• 👉 Installation chapter in the documentation (German): https://docs.billingcat.de/de/docs/install/

The manual covers:

• local development setup (SQLite)
• configuration via config.toml
• running migrations
• production deployment (e.g. with PostgreSQL)
• PDF generation via speedata Publisher
• e-mail setup

If you just want to experiment locally, the very short version is:

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 registered user becomes the admin user.

For all details and edge cases, please refer to the documentation.

Getting started

If you:

• want to self-host billingcat → read the [installation section in the installation guide]
• want to just try it as SaaS → keep an eye on https://billingcat.de and subscribe to the newsletter.

For local hacking, a minimal workflow looks like this:

git clone https://github.com/billingcat/crm.git
cd crm
cp config.toml.example config.toml
go run -tags sqlite .

More complete setup instructions (production, databases, mail, PDF, …) live in the manual.

License

billingcat is dual-licensed:

• Open Source: released under the GNU Affero General Public License v3.0 (AGPL-3.0). That means if you modify and use billingcat as a service, you need to publish your changes. See the LICENSE file for details.

• Commercial License: if you want to use billingcat without the AGPL requirements (e.g. inside proprietary products or SaaS offerings), get in touch.

  Contact: [[email protected]]

Trademarks & Logos

The billingcat name is a registered trademark of Patrick Gundlach. The name and the billingcat logo are not part of the open-source license. Forks or self-hosted instances should replace them with their own branding.

Contributing

Pull requests, bug reports and ideas are always welcome! Just open an issue or a PR here on GitHub.

Third-Party Licenses

This project makes use of third-party libraries like Alpine.js, Tailwind CSS and Font Awesome (see Notice.md).

Made with ❤️ by a small business, for small businesses.