API

APIs sit between an application and the web server, acting as an intermediary layer that processes data transfer between systems. Here’s how an API works:

A client application initiates an API call to retrieve information—also known as a request. This request is processed from an application to the web server via the API’s Uniform Resource Identifier (URI) and includes a request verb, headers, and sometimes, a request body.
After receiving a valid request, the API makes a call to the external program or web server.
The server sends a response to the API with the requested information.
The API transfers the data to the initial requesting application.

While there are many aspects of API testing, it generally consists of making requests to a single or sometimes multiple API endpoints and validating the response. The purpose of API testing is to determine if the API meets expectations for functionality, performance, and security.

The most used API is a RESTful API (Representational State Transfer API). RESTful APIs allow for interoperability between different types of applications and devices on the internet.

REST API Testing is a web automation testing technique for testing REST-based APIs for web applications without using the user interface. The purpose of REST API testing is to record the response of REST API by sending various HTTP requests to check if REST API is working correctly. You can test a REST API with GET, POST, PUT, PATCH and DELETE methods.

Speedscale helps operation teams prevent costly incidents by validating how new code will perform under production-like workload conditions. Site Reliability Engineers use Speedscale to measure the golden signals of latency, throughput and errors before the code is released. Speedscale Traffic Replay is an alternative to legacy API testing approaches which take days or weeks to run and do not scale well for modern architectures.