CAMPR - Open source project management tool with 16 modules

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.

Hassl - A really great project management app

Nifty - Manage projects, work, and communications in one place.

Confleo - Confleo is an all-in-one project management and CRM tool that allows you to create and manage multiple projects, assign multiple users within it, create stunning invoices for your clients and even accept payments from them through in-built payment g…

productboard - Beautiful and powerful product management.