Mosparo is a self-hosted, open-source spam protection system that replaces CAPTCHA on web forms. It is built as a monolithic Symfony 6.4 application (PHP 8.1+) with Doctrine ORM supporting MySQL, PostgreSQL, and SQLite. The system provides a multi-tenant architecture where each project (website) can define custom spam detection rules (field rules for words, emails, domains, IPs, user agents, etc. and submission rules like random value detection) and security measures (honeypot, minimum time, proof-of-work, request delaying, IP lockout, equal submission blocking). Integration is done via a frontend JavaScript widget that communicates with a verification API. The codebase also includes an administration panel for system settings, user management, GeoIP2 integration, rule package imports, statistics, and self-update capabilities. The architecture follows standard Symfony patterns with controllers, services (helpers), repositories, and Twig templates. The rule engine is extensible via interfaces and is reasonably well-tested at the unit level. The project is actively maintained with a robust CI/CD pipeline and Docker support.