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
A self-organizing Obsidian vault that gives AI coding agents persistent memory. Claude Code, Codex CLI, Gemini CLI.
Claude Code plugin that generates individualized knowledge systems from conversation. You describe how you think and work, have a conversation and get a complet
A plain text note-taking assistant
Get tasks and ideas out of your head. A free GTD to-do app for desktop and mobile. Works offline, no account needed
PM Brain OS: The Second Brain for Product Managers, Made of Markdown
Related tags
Frequently asked questions
How many open source second-brain projects are there?
This registry tracks 6 projects tagged second-brain, with 57,678 GitHub stars between them. The most-adopted is openhuman at 42,503 stars.
Are these second-brain projects free to use?
Yes — 6 of the 6 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?
4 of the 6 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.