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.
RemindUs - Advanced reminders for Slack teams
Agile Tools for Trello - The one power-up all agile teams using Trello need
Slack - A messaging app for teams who see through the Earth!
Trello for Slack - Organize anything with anyone, inside Slack
Workplace by Facebook - Connect everyone in your company and turn ideas into action.