Est. for the thoughtful — a second brain
A quiet place
to think, to keep,
to remember.
Cortex is a note-taking app for people who take their ideas seriously. Capture them like ink on paper — and let them grow into a library of your own mind.
We don’t remember our lives. We remember the notes we kept about them. Cortex makes sure those notes are still there — and still talking to each other — decades from now.
— The Cortex manifesto
Three principles
Write first, organize never
Folders are a tax on thought. Cortex lets you write freely; structure emerges later, on its own, through the links you make.
Nothing is ever lost
Every note is indexed the instant you type it. Ask a question in plain words and your past self answers, citing the page.
Ideas compound
A note you wrote two years ago resurfaces beside today’s thought. Over time, your second brain grows wiser than the first.