local-first · markdown-native · self-hostable sync
Your notes, compiled into a second brain
Cortex indexes everything you write, links it automatically, and answers questions about your own mind — in under 40ms, entirely on device.
brew install cortex
features
No plugins to babysit. No cloud lock-in. Just notes that behave like a well-indexed codebase.
Quick-capture everywhere
Global hotkey → thought saved. Clipboard, URL, voice, and screenshot all become searchable notes in under a second.
Graph, not folders
Every note gets wired to related notes automatically. Explore your thinking as a graph or a list — your call.
Ask your past self
Hybrid semantic + keyword search over your entire history. Results cite exact lines, with diffs against your edits.
Version-controlled
Every change is a commit you can browse, blame, and revert. Git under the hood, zero setup on the surface.
E2E-encrypted sync
Device-to-device CRDT sync. Works offline for weeks, merges without conflicts, self-host if you want.
Plain text forever
Your vault is just Markdown on your disk. Open it in vim if you like. We'll wait. We're local-first, seriously.
by the numbers
Benchmarked on a 10-year, 250k-note vault. Your mileage may vary, but it probably won't.
Replaced Notion, Obsidian, and three browser tabs with one binary that starts in 90ms. My notes now have blame. My notes now have CI. I am unwell, and I love it. sudo_kai, principal engineer, HN thread #41982
ready to compile?
Free and open source. Pro adds sync between more than two devices.