Contao

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.