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Restate vs Windmill

Windmill scores higher on the AgentReady, 64/100 against 59/100. They differ on 7 of the 41 signals. Which ones decides whether an agent can adopt them without a person watching.

What each one is

Restate. Restate is a lightweight runtime to turn AI agents, workflows, and backend services into durable processes.

Windmill. Windmill is a fast, open-source workflow engine and developer platform.

Where Restate is ahead

Restate passes mcp discoverable, and Windmill does not. That is discover, whether an agent can find the product at all without being told it exists.

It also holds adopt: mcp integration available. Windmill misses it.

And on operate, retry behavior documented. Windmill misses it.

Where Windmill is ahead

Windmill passes structured api reference and limits / constraints documented, and Restate does not. That is understand, whether an agent can read the docs and work out how the API behaves before calling it.

It also holds adopt: agent-compatible signup flow. Restate misses it.

And on operate, agent compatibility verified. Restate misses it.

What neither does

Both fail openapi / spec quality, authentication documented, request examples provided, response examples provided, errors and status codes documented, no mandatory sales call, programmatic credential creation, structured, predictable output, machine-readable errors, idempotency support, rate-limit behavior predictable. If your agent needs any of those, you will be building it yourself either way.

Score, pillar by pillar

The AgentReady splits into four pillars, scored separately, because a product can be easy to find and still impossible to adopt.

Discover. Restate leads 100 to 87. Restate misses nothing; Windmill misses mcp discoverable.

Understand is whether an agent can read the docs and work out how the API behaves before calling it. Windmill leads 46 to 23. Restate misses structured api reference, openapi / spec quality, authentication documented, request examples provided, response examples provided, errors and status codes documented, limits / constraints documented; Windmill misses openapi / spec quality, authentication documented, request examples provided, response examples provided, errors and status codes documented.

Adopt. Restate leads 70 to 67. Restate misses no mandatory sales call, agent-compatible signup flow, programmatic credential creation; Windmill misses no mandatory sales call, programmatic credential creation, mcp integration available.

Operate. Windmill leads 56 to 41. Restate misses structured, predictable output, machine-readable errors, idempotency support, rate-limit behavior predictable, agent compatibility verified; Windmill misses structured, predictable output, machine-readable errors, retry behavior documented, idempotency support, rate-limit behavior predictable.

Pricing

Restate starts at $0/mo and has a free tier. Windmill does not publish one and has a free tier.

Signal by signal

Which to pick

Windmill clears more of the signals an agent needs, so it is the safer default for unattended use. Full profiles: Restate and Windmill. Alternatives to each: Restate, Windmill.

An agent can fetch this as data: POST /v1/compare {"slugs": ["restate", "windmill"]}