paironce

Send files and text from a terminal to your own phone or computer with PairOnce. Pair once with a six-digit code; after that, npx paironce send report.pdf puts the file on your phone. End-to-end encrypted, direct between the devices whenever the network allows, and through an encrypted relay when it does not. No account.

npx paironce pair                 # shows a code: type it at paironce.com on your phone
npx paironce send build.zip       # sends to the paired device
npx paironce text "https://example.com/some/long/link"
npx paironce receive --to ./inbox # receives files sent from the phone

The other device is any browser with https://paironce.com open: iPhone, Android, Windows, Mac or Linux. Nothing to install there.

Commands

--name "<name>" (or the PAIRONCE_NAME variable) sets what the other device shows for this one, for example --name "Build server". The key stays the same, so paired devices still know it.

When a paired device is not connected, the command asks it to connect: PairOnce on that device shows "Windows · Terminal wants to reconnect" with a Connect button.

Related MCP server: Covalent Bond

Use it from an AI agent (MCP)

paironce mcp gives an agent five tools:

The agent reaches only devices you paired and approved, and nothing arrives anywhere unasked.

Claude Code:

claude mcp add paironce -e PAIRONCE_NAME="Claude Code · Agent" -- npx -y paironce mcp

Other clients (Cursor, Claude Desktop and others), in their MCP configuration:

{ "mcpServers": { "paironce": { "command": "npx", "args": ["-y", "paironce", "mcp"], "env": { "PAIRONCE_NAME": "Cursor · Agent" } } } }

Then ask: "pair with my phone", "send the build log to my phone" or "I'll send you a photo of the error from my phone".

How it works

The CLI runs the same connection code as paironce.com: the PairOnce protocol and @paironce/core for pairing and encryption, with WebRTC from node-datachannel for direct connections and @roamhq/wrtc (libwebrtc) for the relay. Files and messages are encrypted on this computer and decrypted on the other device; the PairOnce service only introduces the two devices and, when needed, relays encrypted bytes it cannot read.

This computer's device key and the list of paired devices are kept in ~/.paironce (or $PAIRONCE_HOME), readable only by you. The private key never leaves this computer.

It connects directly whenever the networks allow it, otherwise through the encrypted relay over UDP, TCP or TLS on port 443, and where even that is blocked, through the PairOnce tunnel: the same encrypted data over a secure WebSocket to paironce.com. So it works on servers, in containers that block UDP, and behind a web proxy (HTTPS_PROXY is used automatically). In a cloud sandbox with an allow-list, such as Claude Code on the web, add paironce.com to the allowed domains. PAIRONCE_DEBUG=1 shows each step of connecting.

Requires Node.js 22 or later on Windows, macOS (x64 and arm64) or Linux (x64 and arm64).

License

Apache-2.0. PairOnce is a trademark of its owner; see https://paironce.com.