Chapter 6 – Test Tools
Mock Service Worker (MSW) – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
A library that intercepts requests at the network level using service workers for browser and Node, enabling seamless API mocking in tests.
In simple words
A library that fakes API responses in browser and Node tests.
Exam tip
MSW is the modern JS mocking standard — same mocks work in dev, test, and Storybook.
Related terms
Practice this term in the ISTQB Mock Test
40 CTFL v4.0 questions, 60-minute timer, instant scoring and chapter-wise breakdown.
Practice in Mock Test