A real-time shared clipboard. Open the page on two devices, type or paste on one, and it appears on the other within a few hundred milliseconds. You can also send files between devices. Runs on Cloudflare Workers with a Durable Object for the live sync.

• One shared pane — both devices edit the same text; last write wins.
• Password = room — the password you type names the room. Use the same one on both devices and you share a pane; a different password is a different room.
• File sharing — send a file up to 50 MB by button, drag-and-drop, or paste. Transfers stream between the connected devices and are never stored on the server.
• 2-person rooms, adjustable — a room starts capped at 2 people. Any member can raise or lower the limit from inside the room.
• Ephemeral — each room lives for 1 hour from creation, then clears itself. Reconnecting afterward starts a fresh, empty room.

Security model

The room password is the only credential, so CopyTo is built to keep it from leaking and to make guessing expensive:

• The password never leaves the browser. It is hashed with SHA-256 in the client, and only that hash is sent. The hash names the Room Durable Object, so the same password reaches the same room without the server ever seeing it.
• The key is not in the URL. It travels in the WebSocket subprotocol header, not a ?query, so it can't leak through URL logs, browser history or Referer.
• Edge rate limiting. A Cloudflare rate-limiting binding caps WebSocket connection attempts per IP (20 / minute) before they reach the room logic.
• Per-IP room cap. An IpLimiter Durable Object allows at most 5 distinct rooms per IP per hour. Since every wrong password is a different room, this throttles guessing to 5 tries/hour from one address. Refusals are logged.
• Strong passwords. The gate can generate a 20-character random password (~117 bits). A room's secrecy rests on the password being hard to guess, so a long random one is the real defense; per-IP limits slow, but do not stop, a distributed attempt.

How it works

• The Worker serves a single HTML page and upgrades /ws to a WebSocket. The room key arrives in the Sec-WebSocket-Protocol header.
• Each Room holds the current text, relays text and file chunks to the other connected clients, tracks the member limit, and arms a 1-hour alarm on creation. When the alarm fires it clears the room and closes connections.
• Files are chunked (~700 KB base64 per message) and relayed through the room to the other members, reassembled client-side. Nothing is persisted server-side, so a file only reaches devices connected at the time it is sent.

Setup

npm install

There is no server-wide password to configure — rooms are created on demand by whatever password a user enters (minimum 6 characters).

Run locally

npm run dev

Open the printed localhost URL in two browser windows, enter the same room password in each, and type.

Deploy

npm run deploy

Custom domain (copy.jaba.ge)

After the first deploy, attach the domain either in the Cloudflare dashboard (Workers & Pages → your Worker → Settings → Domains & Routes → Add custom domain) or by uncommenting the routes block in wrangler.toml and redeploying. The domain must be on the same Cloudflare account.

Notes

• Text is capped at ~1 MB per update; files at 50 MB.
• Tuning constants live at the top of src/worker.js: ROOM_TTL_MS (room lifetime), MAX_ROOMS_PER_IP, DEFAULT_MAX_MEMBERS, and HARD_MAX_MEMBERS. The edge rate limit is configured in wrangler.toml under [[unsafe.bindings]].
• Watch refused attempts live with npx wrangler tail (look for [room-limit] and [rate-limit]).