Beekeeper Studio : Open Source cross-platform SQL Editor and Database Manager. Use Beekeeper Studio to query and manage your relational databases, like MySQL, Postgres, ...
Fun Retro : Easy to use and beautiful restrospective board.
Taiga.Io : Taiga is a project management platform for startups and agile developers & designers who want a simple, beautiful tool that makes work truly enjoyable...
Matrix : Matrix is an open standard for decentralised communication, providing simple HTTP APIs and open source reference implementations for securely distribu...
Kinto : Kinto is a lightweight JSON storage service with synchronisation and sharing abilities.
Imagine running your favorite Windows applications and drivers in an open-source environment you can trust. That's ReactOS. Not just an Open but also a Free operating system.