PartyKit

PartyKit is an open source deployment platform for AI agents, multiplayer and local-first apps, games and websites... It works well with popular collaboration frameworks and libraries. Y.js, Automerge, Replicache, XState, tldraw, TinyBase, they all Just Work. PartyKit integrates with your current setup. Plays nicely with Vercel, Netlify, AWS, Cloudflare, fly.io, or wherever you host your app. No big rewrite needed. Standards-based: WebSockets, Fetch, Request-Response, Wasm. https://www.partykit.io/

Apr'2024: acquired by Cloudflare, so now free/built-in when hosted there.