SuiteCRM

SuiteCRM is a fully open source customer relationship management platform that extends far beyond basic contact tracking. It includes built-in billing automation for generating invoices, managing recurring subscriptions, and processing payments through integrated gateways. The system is actively developed by the community with regular security updates and new feature releases.

The software runs on Linux and Windows servers using PHP and MySQL or MariaDB. It supports payment integrations with Authorize.Net, PayPal, Stripe, and other gateways, along with automated invoice generation and quote-to-cash workflows. SuiteCRM also offers modules for opportunity management, email marketing, and customer service, all tied into the same billing data. The project is maintained by SalesAgility and has been forked from SugarCRM Community Edition.

There is no paid tier or feature gating. Everything is available under AGPLv3. SuiteCRM is well suited for small to medium businesses that want to keep their billing and CRM in one system without per-user licensing fees. The software is used by tens of thousands of organizations worldwide.