API Automation: First Steps

Once you can test APIs manually (e.g. with Postman), the next step is automation: run the same checks on every build and catch regressions early. This post is a detailed guide to tools, project structure, practices, and running API tests in CI—with concrete examples so you can start quickly.

Why automate API tests

• Fast and stable: No browser or DOM; tests run in seconds and are less flaky than UI tests. You can run hundreds of API tests in a few minutes.
• Early feedback: Run as soon as the API is deployed (e.g. in CI after build). Catch breaking changes before they reach staging or production.
• Regression: Same tests run on every change; contract and behavior drift are caught quickly.
• Coverage: Many user flows are driven by APIs; automating API tests gives broad coverage with fewer tests than UI-only automation.
• CI/CD fit: API tests integrate easily into pipelines; most tools support CLI and exit codes so the build fails when tests fail.

Tool comparison in depth

Postman + Newman

What it is: You build requests and tests in the Postman UI; Newman runs the same collection from the command line.