Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.

Instabug - The top apps in the world rely on Instabug for beta testing, user engagement and crash reporting.

Anchor CMS - Free and lightweight blogging system

Bird Eats Bug - Saw a bug? Send an instant replay to engineers. It will come with console logs and everything. Developers will ❤️ you.

Textpattern - Textpattern is an elegant content management system that is free, open source software.

Sentry.io - From error tracking to performance monitoring, developers can see what actually matters, solve quicker, and learn continuously about their applications - from the frontend to the backend.