Prism vs Specmatic

Free and open source

Free tier available

Free and open source. You pay in engineering time and CI minutes.

Open source core; commercial support and an enterprise insights product are sold separately.

Everything, self-hosted

Open-source core covering contract testing and stubbing.

Established

Stoplight (SmartBear) · since 2017

Emerging

Specmatic · since 2020

• 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.

• Spec-driven rather than consumer-driven, so it needs far less cross-team process than Pact.
• The same spec produces both the provider test and the consumer mock.
• Covers async messaging (Kafka, AsyncAPI) as well as HTTP.

• 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.

• Only works if your specs are accurate and maintained.
• Smaller community than Pact, with fewer worked examples.
• Primarily JVM-oriented tooling.

Design-first API teams who want mocks that are provably in sync with the contract.

Spec-first organisations that want contract enforcement without the Pact process overhead.