Stateful serverless actors that run indefinitely, sleep when idle, and persist state across restarts without external database round trips. Rivet provides a vendor-neutral alternative to Cloudflare Durable Objects, delivering long-running processes with co-located in-memory state and per-actor SQLite databases on any infrastructure you choose. The Rust engine comprises four packages: Pegboard for actor orchestration, Gasoline for durable execution, Guard for traffic routing via Envoy, and Epoxy implementing multi-region KV storage through EPaxos consensus. Each actor maintains instant-access in-memory state plus a dedicated SQLite database for relational queries, backed by RocksDB on single nodes or PostgreSQL with NATS pub/sub for multi-node clusters. RivetKit SDKs in TypeScript, Rust, and Python support built-in WebSocket connections, task queues, scheduling, and CRDT-based real-time collaboration. The v2.3 rewrite moved the core runtime from JavaScript to native Rust via WebAssembly, eliminating main-thread blocking across Node.js, Bun, Deno, and Cloudflare Workers. A built-in dashboard provides actor inspection with real-time Prometheus metrics. Deploys as a single Docker container on port 6420 with optional PostgreSQL for persistence. Available on RepoCloud with a dedicated VPS under the Apache 2.0 license.