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.
Freelancer Stack - Curated directory of tools used by 10,000+ freelancers
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.
Alpas - Manage your team's work, projects & tasks online for free.
Jira - The #1 software development tool used by agile teams. Jira Software is built for every member of your software team to plan, track, and release great software.
Blueprint by Gigster - Transform your idea into a plan any dev can build