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    Test what your API really did

    API Test Base is a free, offline‑first tool for testing APIs and their side effects — the records your API writes to a database, the messages it publishes to a queue, the files it creates.

    No account, no cloud. You download it and run it on your own machine or in your CI/CD pipeline. Test cases are created with a no‑code / low‑code UI, so you can be productive in minutes.

    API Test Base test case run result — three steps (set up database data, invoke the HTTP API, check the database) all passed, shown in green with per-step timings

    Verify the side effects, not just the response

    Tools like Postman make it easy to verify an API’s response — and that’s where most testing stops. But real APIs do more: they write to databases, publish messages to queues, upload files, and call downstream services. If your test only checks the response, you may miss what the API actually changed.

    For example, a single POST /orders call can be verified end to end:

    ✓ HTTP response = 200
✓ Order record created in database
✓ Message sent to queue
✓ File uploaded to FTP server
✓ Downstream API called successfully

    API Test Base verifies both the response and these side effects in one automated test case.

    Test APIs triggered by queue messages and file drops

    Not every API is an HTTP endpoint. The same business logic may be triggered by:

    • a message on a queue — IBM MQ, JMS, AMQP, or MQTT
    • a file dropped on an FTP or SFTP server
    • a SOAP call

    API Test Base can send the trigger over the right protocol and then verify the outcome — so you can test the API the same way no matter how it is invoked. That makes it well suited to integration and ESB scenarios such as IBM MQ testing, JMS testing, SFTP testing, and SOAP API testing.

    Built on a method: Integration Unit Testing

    API Test Base is built around Integration Unit Testing — testing an API as a black box, in isolation, by checking both its contract (request and response) and its side effects (database records, messages, files, downstream calls).

    Because the tests know nothing about the API’s internal code, they stay stable as the implementation changes. The same API tests you run by hand during development can be automated in a CI/CD pipeline to run the whole set on every build.

    Learn more about Integration Unit Testing →

    Built‑in test setup for integration testing

    Integration tests need the right state before the API runs, and with most tools that means external scripts. API Test Base runs the setup directly inside the test. A typical database test is three steps in one case:

    Database step
    → clear the table and insert a test record

    HTTP step
    → call the REST API

    Database step
    → query the table and assert the updated values

    Setup isn’t limited to seeding data. For full isolation, a setup can stand up a dedicated stub database — a real database such as PostgreSQL, running in a throwaway Docker container — and create its schema and tables, so the API runs against state that’s entirely the test’s own. Structured test setup lets you define each setup once, reuse it across folders, and run only what’s needed.

    Feature highlights

    Ready to get started?

    Download API Test Base and write your first test in minutes — then run the same tests in your CI/CD pipeline.