Prism vs Tonic.ai

Free and open source

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

Enterprise quote-based pricing by data volume and connected databases.

Everything, self-hosted

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Established

Stoplight (SmartBear) · since 2017

Established

Tonic.ai · since 2018

• 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.

• Preserves referential integrity and statistical distribution, so applications behave as they do in production.
• Directly addresses the GDPR and HIPAA exposure created by production data in lower environments.
• Subsetting produces a small but coherent slice rather than a full copy.

• 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.

• Expensive, with enterprise-only pricing.
• Initial configuration of sensitive-field classification takes real effort.
• Adds a pipeline stage that must be maintained as the schema evolves.

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

Organisations that currently copy production data into staging and know they should stop.