Prism vs Snaplet Seed
Feature checklists rarely decide anything. What decides it is the pricing metric, who has to write the tests, and which limitation you can live with.
Entry price
Free and open source
Open sourceFree and open source
Open sourceWhat drives the bill
The metric that actually scales your invoice.
Free and open source. You pay in engineering time and CI minutes.
Free and MIT-licensed. Snaplet the company shut down in August 2024 and snaplet.dev no longer resolves; this is a community-held library, not a service.
Free tier
Everything, self-hosted
Everything, self-hosted
Open source
Apache-2.0
MIT
Self-hostable
No-code authoring
Languages
Platforms
Fits teams
Adoption
Established
Stoplight (SmartBear) · since 2017
Emerging
Supabase community (formerly Snaplet) · since 2021
Strengths
- 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.
Limitations
- 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.
- Effectively unmaintained: the last npm release (0.98.0) was July 2024 and the last commit to the default branch was August 2024, though the repo is not archived.
- PostgreSQL-centric.
- TypeScript ecosystem only.
Best for
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.
All of these integrate with: GitHub Actions.
Pricing last reviewed August 2026 and is indicative only — confirm on each vendor’s own page.