Testcontainers vs Mock Service Worker

Free tier available

Free and open source

Free. Testcontainers Cloud, which offloads container execution, is a paid Docker product.

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

The libraries are free and open source.

Everything, self-hosted

Category standard

AtomicJar (Docker) · since 2015

Category standard

OSS community · since 2020

• Tests run against the real database engine, so dialect and behaviour differences surface early.
• Containers are disposable, which removes shared-state flakiness entirely.
• Excellent language coverage with idiomatic APIs.

• 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.

• Requires a Docker daemon in CI, which not every environment provides.
• Container startup adds seconds to each test run unless reused carefully.
• Heavier resource usage than in-memory alternatives.

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

Integration tests that currently use in-memory databases and lie to you.

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