Contao

Contao is an open‑source content management system designed for building professional websites and scalable web applications. It follows open web standards, offers built‑in support for multilingual sites, detailed user permissions, and a modular architecture that can be extended through a range of bundles such as Calendar, News, and Newsletter. The platform emphasizes accessibility, complying with BITV 2.0 and BFSG, and includes features like Double‑Opt‑In and automatic XML‑sitemaps to meet GDPR and SEO requirements.

Target users include agencies, companies, and developers who need a self‑hostable, free‑tier CMS that can be customized without a subscription. Its intuitive backend helps editors navigate content, while developers can manage dependencies via Composer, run automated tests, and build assets with Node.js. The project is maintained under LGPL‑3.0, has a stable release history since 2006, and provides long‑term support for LTS versions.

Distinctive aspects are its focus on accessibility and data‑privacy out of the box, a monorepo that splits core functionality into separate Composer packages, and a managed edition that simplifies local development and contribution workflows. Continuous integration, code‑quality tools, and a strong community of partners support ongoing maintenance and feature development.