Contao
Contao is an open-source PHP CMS for building professional, accessible, SEO-friendly and performant websites and web applications; extensible via Symfony bundles and Composer.
Contao is an open-source content management system written in PHP that provides a full-featured CMS and web-application framework built on top of the Symfony full-stack framework. It targets professional websites and portals with a focus on accessibility, SEO, performance and predictable long-term support.
Key Features
- Symfony-based architecture with modular bundles and events/hooks for extensibility
- Contao Manager: a graphical Composer frontend for installing, updating and recovering installations
- Built-in SEO capabilities: editable meta tags, schema.org support and automatic XML sitemap generation
- Accessibility focus with compliance guidance for common European accessibility standards
- Performance features including deferred image resizing, support for HTTP/2, ESI and compatibility with HTTP caches (e.g., Varnish)
- Security features: modern password hashing, optional 2FA/passkeys, automatic account lockout and a public security advisory process
- Multi-site and multilingual support plus granular user permissions out of the box
- Managed Edition and Composer/Symfony bundle installation options to support varied deployment workflows
Use Cases
- Building accessible, SEO-optimized corporate websites, microsites and marketing portals
- Multi-language or multi-site deployments where centralized management and fine-grained permissions are required
- Integrating CMS features into existing Symfony applications via Contao’s bundle architecture
Limitations and Considerations
- Official database support is limited to MySQL/MariaDB (Contao uses Doctrine DBAL); other database engines are not officially supported
- Server requirements expect modern PHP versions and extensions; upgrading PHP or dependencies typically requires a Composer update and may require attention to installed third-party extensions
Contao is aimed at teams and agencies that need a stable, extensible CMS with a strong emphasis on accessibility, security and predictable LTS cycles. Its Symfony foundation and Composer-based workflow make it suitable both as a standalone CMS and as an embeddable bundle for Symfony applications.