Rivet launches open-source actor orchestrator for scaling AI agents with S3-backed storage

Rivet, a Y Combinator F25 startup, has launched an orchestrator that runs AI agents as lightweight actors instead of heavyweight sandboxes. Each actor offers long-lived processes, in-memory state, WebSocket support, and durable SQLite storage, and it hibernates when idle. The company says its actors use far less memory and start much faster than sandboxes, and the platform is open source and self-hostable. Rivet stores data primarily on S3, using an SSD tier to keep write and read speeds high while cutting costs. The company cites a customer, Amp, that migrated its multiplayer agents to Rivet after running into limits on Cloudflare Durable Objects.