Tell us about API testing.

API testing is the process of verifying the correctness, performance, and security of application programming interfaces.

Main types of API testing:

• Functional — checking that the API returns correct data and handles requests properly.
• Integration — testing the interaction of the API with other system components.
• Load — assessing how the API performs under high load.

Example of a REST API test using curl:

curl -X GET https://api.example.com/users/123 -H "Authorization: Bearer token"

It checks that the response contains the expected data and a status code of 200.

For automation, tools like Postman, SoapUI, JMeter are often used, and tests are also written in programming languages with libraries for HTTP requests.