The open-source, local-first NotebookLM alternative — Cortex turns your lectures, PDFs, slides and recordings into cheatsheets you can trust, flashcards, quizzes, audio overviews and a chat scoped to exactly what you ask, with citations back to the source. Keyboard-first. Quietly beautiful.
Not another whitespace-heavy note app. Cortex is information-first, organised the way you actually study — Subjects, Topics, Sources — with the AI doing the synthesis you'd never have time for.
Completeness-checked, approve-to-merge. Add a source and Cortex drafts updates into enforced sections — then shows you a diff. Accept all, accept a section, or reject. Nothing changes until you say so. The answer to NotebookLM's silent deletions.
Subjects → Topics → Sources. A collapsible tree, not a flat pile of notes.
Turn any topic into a two-host audio deep-dive with a synced transcript.
Ask within one source, a topic, or a whole subject. Click the breadcrumb to widen or narrow — citations link straight back to the page.
Modal navigation, a command palette, and a space-leader hint pane. Mouse works too — every action has a path.
Press one key and Cortex starts listening — a live waveform and a rolling transcript while you record. Stop, and it files itself as a fully transcribed, searchable, citable source under the right topic.
Okay, so recursion — the key idea is a function that calls itself on a smaller input.
You need a base case, otherwise it never terminates and you blow the stack.
And the interesting property is overlapping subproblems▋
Upload PDFs & slides, paste a URL or YouTube link, record a lecture, or snap a photo to OCR.
Parse → chunk → embed, locally or on your homelab. Sources become searchable and citable.
It drafts a sectioned cheatsheet, flashcards, quizzes and audio overviews — you approve the merges.
Run flashcard sessions, take quizzes, and chat scoped to any source — all keyboard-driven.
Ten built-in palettes, every surface at AA contrast. On Omarchy Linux, Cortex can follow your desktop theme automatically. Gruvbox, Tokyo Night, Catppuccin, Nord, Dracula, Everforest, Rosé Pine, Kanagawa, Solarized and Osaka Jade.
↑ Click a palette to preview the whole page in that theme
Cortex started as a frustration. Existing tools either buried dense material in whitespace, or quietly dropped the exact point you needed at 2am before an exam. We wanted something that respected information density and your trust in equal measure.
So we built a study OS the way we'd build a dev tool: keyboard-first, local-first, fast, and honest about what it changes. It reads your Omarchy theme, runs heavy jobs on your own homelab, and never sends your notes anywhere you didn't choose.
"We build the tool we wish we'd had in our final year — and we use it every single day."
Free and source-available. Native desktop on Linux, macOS and Windows — plus iOS in TestFlight beta.
Install, paste your key, detect your theme, and create your first subject in five minutes.
Read guide →The full modal map — Normal, Insert and Select modes, the leader pane, and how to rebind.
View cheatsheet →Route each task to Gemini, Claude, OpenAI or local Ollama — and offload to your own hardware.
Configure →