GitKraken Timelines - Communicate major project milestones and deadlines for free
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.
GitKraken - The intuitive, fast, and beautiful cross-platform Git client.
Roadmap - Collision avoidance for projects and people
Tables by Google - Tables helps teams easily track & automate tasks
Chronologies.io - Your Memories, Your Story, Your Timeline