The best open source alternative to Favro is Focalboard, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 50 alternatives to Favro and seven of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Favro are Jira Clone (Free, Open Source), Leantime (Freemium, Open Source), Planka (Free, Open Source) and GroupThinq (Freemium, Open Source).
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.
Free: Open source with Apache license. No plans. No limits. You can install it in your own servers. Flexible: You have the complete source code in Java, based in OpenXava framework. So hiding features or adding new ones is extremely fast and easy.