Open source prototyping projects
Every project in the registry tagged prototyping, ranked by real GitHub adoption.
Open-source UI design and prototyping for product teams
The Pencil Project's unique mission is to build a free and opensource tool for making diagrams and GUI prototyping that everyone can use.
Charm: A Framework for Rapidly Prototyping Cryptosystems
Frequently asked questions
How many open source prototyping projects are there?
This registry tracks 3 projects tagged prototyping, with 70,650 GitHub stars between them. The most-adopted is Penpot at 60,136 stars.
Are these prototyping projects free to use?
Yes — 3 of the 3 carry an explicit open-source licence across 3 distinct licences, so there is no licence fee. Where a project also sells a hosted or enterprise version, the self-hosted path remains free.
Which prototyping project should I choose?
The list above is ranked by GitHub stars, but stars measure attention rather than fit. Check three things on each card: the licence (permissive versus copyleft), the language it is written in, and the last-push date — a high-star project that has not been pushed in a year is a liability.
Are these prototyping projects still maintained?
2 of the 3 were pushed in the last 90 days, and every card shows its exact last-push date so you can see the rest. Sort your shortlist by that date before committing to a migration.