What should I use for API testing with OpenAPI specs?

If you have OpenAPI specs and want to do API testing, the best tool depends on what kind of testing you mean:

1. Postman

• Great for manual testing, exploratory testing, and sharing collections.
• Can import OpenAPI/Swagger specs and generate requests automatically.
• Good if you want a friendly UI and some automation.

2. Swagger UI / Swagger Editor

• Best for quick validation and trying endpoints directly from the spec.
• More for documentation + basic request testing than serious test automation.

3. Hoppscotch

• Lightweight, fast, browser-based alternative to Postman.
• Supports OpenAPI imports.
• Good for quick ad hoc testing.

4. Insomnia

• Good for API testing workflows and OpenAPI import.
• Clean UI, supports environments and scripting.
• Often preferred for a simpler experience than Postman.

5. Dredd

• Best if you want contract testing against an OpenAPI spec.
• Validates that your API implementation matches the spec.
• More automated/CI-friendly than GUI tools.

6. Schemathesis

• Excellent for property-based and fuzz testing from an OpenAPI spec.
• Automatically generates lots of test cases to find edge cases and bugs.
• Very useful for deeper testing in CI.

7. Newman / Postman CLI

• If you use Postman collections, this is for running them in CI/CD.

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My practical recommendation

• Manual / exploratory testing: Postman or Insomnia
• Spec validation / contract testing: Dredd or Schemathesis
• CI automation: Newman/Postman CLI or Schemathesis

If you want, I can also recommend the best tool based on your exact setup (language, CI/CD, team size, and whether you need manual vs automated testing).