Multiplayer Backend for Browser Games

Why browser games fit this API

• Works from a static page — every endpoint answers CORS preflights; host your game on any static host and it can still manage accounts, rooms and leaderboards.
• Realtime without servers — the WebSocket relay pushes room traffic between browsers; you write game code, not infrastructure.
• Zero-dependency SDK — the JavaScript SDK is plain ESM you can drop into a bundler or serve as-is; no framework required.
• Persistence for free — player data and game data JSON survive sessions, devices and page reloads.

Fits these genres well

Turn-based and async games, card and board games, trivia and party games, co-op sessions, .io-style casual arenas, 1v1 duels, and any game where a reliable ordered message channel is fast enough — which is most of what ships on the web. The WS lane carries the full feature set in every modern browser.

Where it's honest to look elsewhere or hybrid: twitch-rate authoritative simulation in-browser (no UDP from web pages — run a Node.js authority with the same SDK instead), and WebTransport-only designs (not offered today — see the WebTransport explainer).