Zeplin - Collaboration app for UI designers & frontend developers
Firepad - Open source collaborative code and text editing that relies on Firebase for real-time data...
Abstract - A secure, version-controlled hub for your design files
CryptPad - CryptPad is a collaborative office suite that is end-to-end encrypted and open-source.
Mightytext - Send & Receive SMS Text Messages from your computer. Sync'd with your Android #
eduPad - Real-time collaborative text-editor. No account required. Edits highlighted in authors color.