APIs for Beginners
Tags: microservices, api
Published: 2022-01-06 13:28:25

Are you looking to benefit from automation but lack the experience to leverage an API? To equip you with the tools you need to start utilizing APIs and automation, we’ve put together these helpful Beginner FAQs covering common terminology, methods, and tools for testing APIs.

## What is an API?

API stands for Application Programming Interface. An API is a set of programming code that enables data transmission between one software product and another.

## How does an API Work?

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:

1. 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.
2. After receiving a valid request, the API makes a call to the external program or web server.
3. The server sends a response to the API with the requested information.
4. The API transfers the data to the initial requesting application.

## What is API Testing?

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.

## What is the most popular kind of API?

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.

## What is REST?

Representational State Transfer (REST) is a software architectural style that developers apply to web APIs. REST relies on HTTP to transfer information using requests, called ‘URLs’, to return specified data, called ‘resources’, to the client. Resources can take many forms (images, text, data). At a basic level, REST is a call and response model for APIs.

## What is a REST API?

A REST API conforms to the design principles of the REST, or representational state transfer architectural style. Restful APIs are extremely simple when it comes to building and scaling as compared to other types of APIs. When these types of APIs are put into action, they help facilitate client-server communications with ease. Because RESTful APIs are simple, they can be the perfect APIs for beginners.

## What is REST API Testing?

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.

## What is the most Popular Response Data Format?

JSON is the most popular response data format amongst developers. JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write and it’s simple for machines to parse and generate. Plus, JSON is a is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. JSON is widely used due to its lighter payloads, greater readability, reduced machine overhead for Serialization/Deserialization and easier consumption by JavaScript. These properties make JSON an ideal data-interchange language.

## How Can I Improve My API Testing & Performance?

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.

Now that you know some of the basics of APIs and API testing methods, you’re one step closer to being able to leverage the full power of API automation. [Learn how Speedscale’s solutions can help improve your API testing & performance](https://speedscale.com/api-testing/).