Restack (restack.io) builds and maintains the open-source Restack AI SDK.

Restack provides a durable-execution backend and SDK for orchestrating reliable, stateful AI agent workflows with automatic retries and recovery.

Distributed as the restack_ai Python package (and a TypeScript equivalent), run against Restack's engine either self-hosted or as a managed cloud service.

Launched in 2024 and actively developed with example repos updated through 2026.

It exists to give AI agent workflows production-grade reliability, replay, and observability similar to workflow engines like Temporal.

Requires the Restack engine (self-hosted via Docker or the managed cloud) plus an LLM provider API key.

Core SDK is open-source, the orchestration engine has a hosted commercial offering, and workflow state runs on infrastructure you control or Restack's cloud.