Taskade - Track progress, collaborate, and chat in one app.

Web Address: https://www.taskade.com/

In their own words:

Taskade is everything we’ve ever wanted in a team productivity tool. One that would let you ideate, organize, and manage tasks together in real-time — and yet was no more difficult to use than a pen and paper.
No steep learning curves. No complex interface. No maze of functionality you might never find your way out of.