{"data":{"slug":"colyseus","name":"Colyseus","tagline":"MIT Node multiplayer rooms with state sync","category":"libraries","categoryName":"Libraries","url":"https://colyseus.io","github":"https://github.com/colyseus/colyseus","pricing":"open-source","hook":"Colyseus is the authoritative multiplayer server a browser game can self-host for nothing.","whatsGood":"MIT. State sync, matchmaking, SDKs for JavaScript, Unity, Defold, Construct 3, Haxe. create-colyseus-app. Site: free forever, even for commercial games. Pair it with Phaser or KAPLAY.","theCatch":"A server framework, not a renderer. Colyseus Cloud has no free tier — it starts at 15 USD/mo. Capacity depends on your code, not a marketed CCU cap.","verdict":"MIT multiplayer rooms. Self-host is the free path; Cloud is paid from dollar one.","addedAt":"2026-09-03","featured":false,"domain":"Graphics & 3D","subSpecialty":"Multiplayer","capabilities":["realtime","rooms","browser"],"surfaces":["Self-host"],"ecosystem":["Node.js","Browser"],"licenseModel":"OSS/MIT","githubStars":7252},"related":[{"slug":"hono","name":"Hono","tagline":"Tiny TypeScript web framework that runs on every runtime"},{"slug":"phaser","name":"Phaser","tagline":"MIT HTML5 2D game framework with scenes, physics, and tilemaps"},{"slug":"pixijs","name":"PixiJS","tagline":"MIT 2D WebGPU/WebGL renderer, not a game engine"},{"slug":"babylonjs","name":"Babylon.js","tagline":"Apache-2.0 3D engine for the web, now on v9"},{"slug":"playcanvas","name":"PlayCanvas","tagline":"MIT WebGL2/WebGPU engine plus an optional hosted Editor"}],"links":{"self":"/api/gems/colyseus","html":"/gems/colyseus","markdown":"/gems/colyseus.md","category":"/api/gems?category=libraries","categoryPage":"/stacks/libraries"}}