Clipboard Sync

Copy on one device, paste on another. This Go example polls your clipboard every 500ms and relays any changes to a paired device over your self-hosted relay, end-to-end encrypted.

Prerequisites

• A running Relayly server (e.g., docker compose up -d)
• Go 1.24 or newer
• macOS for full clipboard support (Linux/Windows receive a warning and no-op)

How it works

Both devices connect to the same relay and pair using a 6-digit code. After pairing, each device watches its own clipboard. When the content changes, it sends the new text to the peer. When a message arrives from the peer, the local clipboard is updated.

Usage

Navigate to the example directory:

cd examples/go/clipboard-sync

Device A — start first, get a pairing code:

go run . --server=ws://localhost:8080

Output:

╔════════════════════════════════════╗
║  Pairing code:  483921              ║
╚════════════════════════════════════╝
Run on your other device:
  clipboard-sync --server ws://localhost:8080 --code 483921

Waiting for peer to connect…

Device B — paste the code:

go run . --server=ws://localhost:8080 --code 483921

Once both sides connect:

Connected as device "clipboard-xxxxxxxxxxxx"
Paired with clipboard-yyyyyyyyyyyy
Clipboard sync active. Press Ctrl+C to quit.

Now copy anything on either device. It will appear in the other device’s clipboard within 500ms.

Flags

Device identity

The device ID is derived from the first 16 characters of the public key, prefixed with clipboard-. You can override it by setting the RELAYLY_DEVICE_ID environment variable:

RELAYLY_DEVICE_ID=my-macbook go run . --server=ws://localhost:8080

The private key is stored at ~/.relayly/clipboard.key and reused across runs, giving each device a stable identity.

Platform notes

Clipboard access uses pbpaste / pbcopy on macOS. On other platforms the read always returns empty and writes print a warning. Pull requests adding Linux (xclip/wl-paste) or Windows support are welcome.

Check out the full source code at examples/go/clipboard-sync.