Snaplet Seed vs Prism

Free and open source

Free and open source

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.

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

Everything, self-hosted

Everything, self-hosted

Emerging

Snaplet · since 2021

Established

Stoplight (SmartBear) · since 2017

• 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.

• 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.

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

• 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.

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

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