What is API Testing?

API testing focuses on validating how systems communicate with each other.

On this page, I break down different types of API testing using simple examples and real testing scenarios.

API Testing Types

API endpoint testing showing response status codes 200, 404, and 500

Endpoint Testing

Testing if an endpoint returns the correct response and status code

API data-driven testing using multiple input datasets

Data-driven Testing

Passes different sets and type of data inputs to an API to ensure it works correctly

API workflow testing with sequential dependent requests

Workflow Testing

Testing multiple API calls that depend on each other.

API performance testing showing response time and load behaviour

Performance Testing

Measuring response time and system behaviour under a variety of conditions.

API security testing showing authentication and vulnerability checks

Security Testing

Checking authentication, authorization, and vulnerabilities.

API contract testing validating request and response structure

Contract Testing

Ensures the communication between a client and on API follows a specific “contract” or set of expectations