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What is Brainstorm?

Brainstorm is a local-first, AI-native operating system for knowledge work. It looks and behaves like a desktop OS — a shell that hosts small, focused apps — except the “computer” is your knowledge, and everything runs on your own machine.

Three ideas define it:

Apps, not features

Section titled “Apps, not features”

The shell itself does almost nothing. It hosts apps: Notes, Database, Files, Graph, a calendar, a code editor, and more. You add the ones you want and ignore the rest. Each app is sandboxed and updates on its own, so the product grows without turning into a single sprawling monolith.

Your data, your disk

Section titled “Your data, your disk”

Your knowledge lives in a vault — a folder of files on your own disk, not a row in someone else’s database. Brainstorm is local-first: it works fully offline, opens instantly, and never requires a server to read or write your own content. When you choose to sync across devices, traffic is end-to-end encrypted and the relay never sees your data. See Local-first & sync.

Permissions you grant

Section titled “Permissions you grant”

Every app and every AI agent runs behind a capability ledger. An app can only touch the data and services you have explicitly allowed — reading a note, saving a file, reaching the network. Nothing is ambient. This is what makes it safe to run third-party apps and autonomous agents over your most important data. See Apps & permissions.

Built on open foundations

Section titled “Built on open foundations”

Brainstorm is built on open building blocks rather than a proprietary format:

  • Block Protocol for interoperable, typed data.
  • Yjs (CRDTs) for conflict-free, real-time collaboration and offline editing.
  • Lexical for rich text.

That means your content is structured, portable, and not locked to one vendor.

Next steps

Section titled “Next steps”