Prism
Turn an OpenAPI document into a mock server that validates as well as responds.
What it is
Prism, from Stoplight, reads an OpenAPI description and serves a mock API from it, generating responses that conform to the schema and validating incoming requests against it. Because the spec is the only input, the mock cannot drift from the contract.
Best for
Where it is strong
- The mock is generated from the spec, so it cannot silently diverge from the contract.
- Validation proxy mode checks that a real implementation matches its own spec.
- Zero configuration beyond having an OpenAPI file.
Where it falls short
- Useless without an accurate OpenAPI document.
- Limited stateful behaviour — it is spec-driven, not scenario-driven.
- Generated example data is uninteresting unless examples are in the spec.
Pricing
Free and open source
Open sourceFree tier: Everything, self-hosted
What drives the bill: Free and open source. You pay in engineering time and CI minutes.
Check current pricing on Stoplight (SmartBear)’s siteFigures are indicative and were last reviewed August 2026. Vendors change pricing often; confirm before you commit.
Works with
What people who use Prism say
No reviews of Prism yet. If you have used it in anger, yours would be the first.
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If Prism is not the right fit, these solve the same problem differently.
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