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Buildkite vs CircleCI

CircleCI scores higher on the AgentReady, 64/100 against 57/100. They differ on 10 of the 41 signals. Which ones decides whether an agent can adopt them without a person watching.

What each one is

Buildkite. CI/CD platform for workflow automation, test optimization, and supply chain security, designed for AI-led workflows and massive scale

CircleCI. CircleCI is a continuous integration and continuous delivery (CI/CD) platform that helps developers automate software delivery.

Where Buildkite is ahead

Buildkite passes pricing understandable and limits / constraints documented, and CircleCI 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: free trial or free allowance and cli available. CircleCI misses those.

Where CircleCI is ahead

CircleCI passes llms-full.txt / full agent docs, and Buildkite does not. That is discover, whether an agent can find the product at all without being told it exists.

It also holds understand: structured api reference and response examples provided. Buildkite misses those.

And on adopt, no mandatory sales call and copyable quickstart. Buildkite misses those.

Finally, on operate, rate-limit behavior predictable. Buildkite misses it.

What neither does

Both fail openapi / spec quality, authentication documented, request examples provided, errors and status codes documented, self-service signup, programmatic credential creation, fast time to first request, machine-readable errors, retry behavior documented, idempotency support, agent compatibility verified. 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. CircleCI leads 100 to 93. Buildkite misses llms-full.txt / full agent docs; CircleCI misses nothing.

Understand. CircleCI leads 38 to 31. Buildkite misses structured api reference, openapi / spec quality, authentication documented, request examples provided, response examples provided, errors and status codes documented; CircleCI misses openapi / spec quality, authentication documented, pricing understandable, request examples provided, errors and status codes documented, limits / constraints documented.

Adopt. CircleCI leads 60 to 55. Buildkite misses self-service signup, no mandatory sales call, programmatic credential creation, fast time to first request, copyable quickstart; CircleCI misses self-service signup, programmatic credential creation, free trial or free allowance, fast time to first request, cli available.

Operate is whether an agent can run against it in production and recover when a call fails. CircleCI leads 59 to 47. Buildkite misses machine-readable errors, retry behavior documented, idempotency support, rate-limit behavior predictable, agent compatibility verified; CircleCI misses machine-readable errors, retry behavior documented, idempotency support, agent compatibility verified.

Pricing

Buildkite does not publish a machine-readable starting price with no free tier. CircleCI does not publish one.

Signal by signal

Which to pick

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

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