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title: Catalyst
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# Catalyst — API testing that scales
Catalyst is a lightweight, declarative HTTP API testing tool. Define tests in TOML, run them locally or in CI, and evolve from smoke tests to full workflows without glue code.
- New here? Start with the [Quickstart](./tutorials/quickstart).
- First suite? Follow [Your First Test](./getting-started/first_test).
- Already testing? Jump to [Guides](./guides/writing-tests) or [Reference](./reference/schema).
Or read the [Overview](./overview) for the why and how.