getjoinable

The self-test for Joinable, the service that makes web games multiplayer.

npx getjoinable test http://localhost:5173/

It opens two headless players on your game's page and checks the multiplayer integration end to end: both players start a round with the same seed, see each other, finish with one result, and can rematch. For lockstep games (RTS, strategy) it's a determinism doctor: one player on Chromium and one on WebKit give random orders, the two simulations are compared tick by tick, and anything that isn't deterministic is named with its file and line. Each failure says what to fix. Made for coding agents as much as for people.

Options: --round 90 (seconds to wait for a round to finish on its own), --headed (show the browsers), --channel chrome (use your installed Chrome with its GPU, for heavy 3D games).

It needs Playwright's Chromium: npx playwright-core install chromium if it isn't installed; lockstep games also want WebKit: npx playwright-core install webkit. The relay is whatever your page's script tag loads from.

For coding agents: the MCP server

npx getjoinable mcp

Starts Joinable's MCP server over stdio. Add it to Claude Code, Cursor or any MCP client as npx -y getjoinable mcp. It gives the agent the Joinable kit (which pattern fits the game, the exact snippet) and runs this self-test, so the agent can wire multiplayer and check its own work. The relay it talks about defaults to https://relay.getjoinable.com (set JOINABLE_RELAY to change it).

Usage ping

Each run sends Joinable one anonymous ping: the command (test or mcp), the MCP tool called, whether the self-test passed, the package version and whether it ran in CI. Nothing else: no game URL, no files, no IP kept, nothing about you or your machine. It tells us whether the tools are used and work. Turn it off with JOINABLE_TELEMETRY=0 (DO_NOT_TRACK=1 works too).