zsync

zsync keeps clipboards in sync across macOS, Linux, and Windows. It connects peers directly over TCP or through a zsyncd relay. It also works on headless machines, where clipboard data is stored in files.

Relay mode encrypts clipboard contents end to end. Clients encrypt before sending; the relay forwards ciphertext without decrypting it.

Build

Requires a stable Rust toolchain.

cargo build --release

The zsync and zsyncd binaries are placed in target/release/.

Quick start: direct connection

Run the daemon on both machines, then connect from one to the other's address:

zsync daemon
zsync connect 192.168.1.10
zsync status

The default TCP port is 43721; use host:port and set ZSYNC_PORT on the listening machine to change it. Direct TCP is unencrypted, so use it only on trusted networks.

Through a relay

Run zsyncd on a reachable server and create a group:

zsyncd daemon
zsyncd group create --domain relay.example.com

The create command prints a zsync:// URI once. On each client, start the daemon with zsync daemon and connect using that URI:

zsync connect 'zsync://...'

Keep the URI private: it contains the group key. zsyncd prints it when the group is created but does not store the key. Clients use the shared key to encrypt and decrypt clipboard payloads with XChaCha20-Poly1305. The relay can see connection details such as group ID, device ID, hostname, and IP address.

Clipboard commands

echo hello | zsync copy   # short form: zsync c
zsync paste              # short form: zsync p
zsync paste --content    # print bytes, including on headless machines
zsync disconnect         # remove all saved peers
zsync daemon stop

Files and images pasted with zsync paste are written to the current directory. For text, zsync paste --path prints the stored clipboard path. Clipboard payloads are limited to 10 MiB. On Linux, native clipboard access uses Wayland (wl-copy/wl-paste) or X11 (xclip/xsel) when available.

Run zsync --help or zsyncd --help for the full command list.