Mock Service Worker vs Tonic.ai
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 sourceQuote on request
Quote onlyWhat drives the bill
The metric that actually scales your invoice.
Free and open source. You pay in engineering time and CI minutes.
Enterprise quote-based pricing by data volume and connected databases.
Free tier
Everything, self-hosted
Free trial.
Open source
MIT
Self-hostable
No-code authoring
Languages
Platforms
Fits teams
Adoption
Category standard
OSS community · since 2020
Established
Tonic.ai · since 2018
Strengths
- One set of handlers reused across unit, component, E2E and local development.
- Application code is completely unaware it is being mocked — no test-only branches.
- Supports REST and GraphQL with the same model.
- 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.
Limitations
- JavaScript ecosystem only.
- Service Worker registration adds a setup step and occasional caching confusion.
- Handlers can drift from the real API without contract verification.
- 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.
Best for
Front-end teams that want one mocking approach across every kind of test.
Organisations that currently copy production data into staging and know they should stop.
Pricing last reviewed August 2026 and is indicative only — confirm on each vendor’s own page.