HTTrack - HTTrack is a free (GPL, libre/free software) and easy-to-use offline browser utility.
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.
SiteSucker - SiteSucker is a Macintosh application that automatically downloads Web sites from the Internet.
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
WebCopy - Cyotek WebCopy is a free tool for copying full or partial websites locally onto your harddisk for offline viewing.
Slack - A messaging app for teams who see through the Earth!