Mock Service Worker vs WireMock

Free and open source

Free tier available

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

Open source is free; WireMock Cloud is a paid hosted service for shared team mocks.

Everything, self-hosted

Open-source WireMock is complete and free.

Category standard

OSS community · since 2020

Category standard

WireMock Inc. · since 2013

• 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.

• Fault and latency injection lets you test the error paths that never occur on demand in a real sandbox.
• Record-and-replay produces a realistic mock from live traffic quickly.
• Runs anywhere: embedded, standalone, container or cloud.

• JavaScript ecosystem only.
• Service Worker registration adds a setup step and occasional caching confusion.
• Handlers can drift from the real API without contract verification.

• Recorded stubs drift from the real service unless you re-record or verify contracts.
• Complex stateful scenarios get verbose in JSON.
• HTTP only — not for message queues or gRPC without extensions.

Front-end teams that want one mocking approach across every kind of test.

Teams whose integration tests depend on third-party HTTP services.