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.
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
KanbanFlow - KanbanFlow is a Lean project management tool allowing real-time collaboration between team members. Supports the Pomodoro technique for time tracking.
Slack - A messaging app for teams who see through the Earth!
Meistertask - MeisterTask is an intuitive task management and collaboration tool.
Asana - Asana project management is an effort to re-imagine how we work together, through modern productivity software. Fast and versatile, Asana helps individuals and groups get more done.