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.
Metalsmith - An extremely simple, pluggable static site generator.
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
Nikola - Nikola is s static site generator tool written in Python.
Slack - A messaging app for teams who see through the Earth!
GatsbyJS - Blazing-fast static site generator for React