Prism vs Snaplet Seed

Free and open source

Free and open source

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

The Seed library is open source and free; note that Snaplet wound down its hosted product, so treat this as a library rather than a service.

Everything, self-hosted

Everything, self-hosted

Established

Stoplight (SmartBear) · since 2017

Emerging

Snaplet · since 2021

• 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.

• Schema-aware generation means the data actually inserts and the app actually works.
• Deterministic seeds make failing tests reproducible.
• Good TypeScript ergonomics with Prisma and Drizzle.

• 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.

• The company wound down its hosted business — evaluate the library's maintenance status before depending on it.
• PostgreSQL-centric.
• TypeScript ecosystem only.

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

TypeScript teams that want each developer and CI run to start from a clean, coherent database.