The best open source alternative to Process Street is Restyaboard, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to Process Street and 18 is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Process Street are HumHub (Freemium, Open Source), TaskBoard (Free, Open Source), fluxday (Free, Open Source) and eXo Platform (Freemium, Open Source).
A Kanban-inspired app for keeping track of things that need to get done. The goal of TaskBoard is to provide a simple and clean interface to a functional and minimal application for keeping track of tasks. It's not trying to be the next Trello or LeanKit.
eXo Platform is an all-in-one digital workplace solution that helps you connect, align and engage your teams around a single interface. You can use it to improve company and peer-to-peer communication, boost collaboration and manage company knowledge.
Leantime is a project management system for small teams and startups. Designed to help you manage your projects from ideation to delivery. Leantime's Idea Manager allows you to store ideas, communicate them with team members, discuss and move them from idea to validation.