What methods and tools do you prefer to use to verify the functionality of an API?

The following methods and tools are commonly used to test API functionality:

• Manual testing with Postman or Insomnia — convenient for quick testing of individual endpoints, request and response verification.
• Automated testing using frameworks — for example, REST-assured (Java), pytest + requests (Python), or Postman Collection Runner with Newman for running tests from the command line.
• Contract testing — using Pact or Swagger/OpenAPI to verify compliance with API specifications.
• Monitoring and load testing — tools like JMeter, Gatling to check API stability and performance.

An example of a simple Python test using requests:

import requests

response = requests.get('https://api.example.com/users/1')
assert response.status_code == 200
assert 'id' in response.json()

This approach allows quick verification that the API returns expected data and handles requests correctly.