id: local-dev
type: guide
owner: justin
reviewed: 2026-10-13

Running it locally

You need Node 24.

npm install
npm test            # the transform, the room and simulated editors
npm run typecheck   # the Worker and the page's script
npm run dev         # builds the page script, then runs wrangler dev

npm run dev fetches wrangler through npx the first time. It serves the page and the Worker on http://localhost:8787 with a local Durable Object and SQLite under .wrangler/.

Two editors

Open http://localhost:8787/#groceries in two windows side by side and type in both. The status line shows the room's version, or "Saving" while an edit waits for its ack.

To see the note without the page:

curl http://localhost:8787/notes/groceries

Watching the protocol

The browser's developer tools show the frames on the socket under the Network tab, on the ws request. You will see one op frame per send, an ack for each, and the other window's ops arriving as op frames with a version. [[wire-protocol]] lists them.

Starting over

Delete .wrangler/state to forget every note.