Open source second-brain projects
Every project in the registry tagged second-brain, ranked by real GitHub adoption.
OpenHuman is an open source agent harness with local-first memory, agent orchestration, and workflows
Claude Code plugin that generates individualized knowledge systems from conversation. You describe how you think and work, have a conversation and get a complet
Get tasks and ideas out of your head. A free GTD to-do app for desktop and mobile. Works offline, no account needed
Frequently asked questions
How many open source second-brain projects are there?
This registry tracks 3 projects tagged second-brain, with 45,385 GitHub stars between them. The most-adopted is openhuman at 39,838 stars.
Are these second-brain 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 second-brain 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 second-brain 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.