Quip - Quip is the modern productivity suite that simplifies your life and helps your team get work done faster.
Working Copy - The powerful Git client for iOS
Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.
gitui - blazing fast terminal-ui for git
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Firefoo - Gain power over your Cloud Firestore data with a smart GUI