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.
TED Notepad - TED Notepad is a portable text editor software that deals with a large variety of text processing tools, supplemental text clipboards, high accessibility through hotkeys, and a customizable number of settings and options.
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
Notepadqq - Notepadqq is a linux clone (identical application) of Notepad++
Slack - A messaging app for teams who see through the Earth!
iNotepad - Write and organize all your texts and notes on Mac.