Local-first, on purpose
Software you can rely on is software that works without permission. OpenBook puts your data where it belongs — with you.
Your device is the source of truth
Pages live locally and load instantly. The network is an enhancement, never a dependency — close the laptop on a plane and keep working at full speed.
Sync is opt-in
Sign in and OpenBook keeps your settings and pages in step across devices. Don't, and nothing leaves your machine. The choice is yours, reversible at any time.
Conflict-free by construction
OpenBook is built on CRDTs (Yjs). Two tabs, two people or one device coming back online all merge cleanly — no "which version do you want to keep?" dialogs.
Open exports, no lock-in
Everything leaves as HTML, PDF or Markdown — including self-contained interactive HTML. Your words and tools are portable by default.
Curious how it works under the hood?
The developer site goes deep on the CRDT model, the block format and self-hosting.