Chapter 2 – Testing Throughout the SDLC
API Testing – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
Testing performed on APIs (application programming interfaces) to verify functionality, reliability, performance and security.
In simple words
Testing at the service boundary — sending requests to endpoints and asserting responses — without a UI.
Exam tip
API testing sits between component and system integration testing and is often the most valuable automation layer.
Related terms
- Integration TestingAfter units work alone, you plug them together and check the seams — API calls, data hand-offs, contracts.
- Test AutomationLetting tools do the repetitive parts of testing — usually execution, but also data generation and reporting.
- Non-Functional TestingHow fast, how secure, how usable, how reliable — the ‘qualities’ around the feature, not the feature itself.
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