Prism vs Mockaroo
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 sourceFrom $60 per year (indicative, Silver)
Free tierWhat drives the bill
The metric that actually scales your invoice.
Free and open source. You pay in engineering time and CI minutes.
Cheap for what it does; higher tiers raise row limits and add API quota.
Free tier
Everything, self-hosted
Free for up to 1,000 rows per download and a limited number of saved schemas.
Open source
Apache-2.0
Self-hostable
No-code authoring
Languages
Platforms
Fits teams
Adoption
Established
Stoplight (SmartBear) · since 2017
Established
Mockaroo LLC · since 2014
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.
- No code required — an analyst or tester can design a dataset themselves.
- Very large library of realistic field types including regional formats.
- Formula fields allow simple business rules between columns.
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.
- Referential integrity across related tables is limited.
- Free-tier row limits are low for realistic volume testing.
- Data is generated on a third-party service, which needs a privacy check for schema sensitivity.
Best for
Design-first API teams who want mocks that are provably in sync with the contract.
Quickly producing a realistic dataset for a demo, a load test or a new environment.
Pricing last reviewed August 2026 and is indicative only — confirm on each vendor’s own page.