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REST API Interview Questions and Answers


REST API (Representational State Transfer Application Programming Interface), also referred to as RESTful API, is an Application Programming Interface (API or web API) that holds to the limitations of REST architectural style and permits communication with RESTful web services. Roy Thomas Fielding, a computer scientist, created REST. Fielding was also one of the principal authors of the HTTP (HyperText Transfer Protocol) specification.

An API is a set of protocols and definitions for creating and assimilating application software. It is sometimes mentioned as an agreement between an information user and an information provider—establishing the content required by the producer(the response) and the content needed from the consumer (the call). 

In other words, if you want to command a computer to pull information or execute a function, an API helps you communicate with the system to comprehend and accomplish the request. 

An Application Programming Interface is a facilitator between the users and the resources/web services. It allows an organization to share information and resources while maintaining control, security, and validation—defining who gets access to what. 

In this article, we will see some of the commonly asked REST API interview questions. These web api questions or api interview questions focus on REST API concepts, its usage and automation use-cases.

Rest API Interview Questions:

These sets of Rest API interview questions focus on the basics and usage and differences between similar Application programming interface. Candidates preparing for job roles that require knowledge of REST API should put these at the top of their list – as the interviews more often than not start with conceptual knowledge checks like these. Some Rest API interview questions can be tricky and may require multi-part answers.

1. What is REST API? Give two examples. 

REST is not a tool, a library, or a protocol; rather it is an architectural style of web service that delivers a mode of communication between computers or systems on the internet. It is a principle that is used as an architectural means of creating a Network-based software system.

REST API concepts translate to an application program interface that is supported by the architectural design of REST. It refers to service, tools, or software that is built on the REST architectural standard. REST takes advantage of HTTP when used for web APIs, although REST can be used on virtually any protocol. The main benefit of REST APIs is that they provide more flexibility. In REST APIs, data is not inhibited to methods or resources. Therefore, it can return various data formats, make multiple types of calls, and even modify structurally with the suitable carrying out of hypermedia. It is an architectural style that developers apply to Web APIs.

Examples of REST APIs

It is recommended to keep these examples as answers of rest api interview questions short and precise.

  1. Twitter provides a REST API which a designer or a developer can query to procure/source the latest tweets, or run a search query that will return the outcomes in JavaScript Object Notation (JSON) format.
  2. Instagram API permits your applications to pull photos, accounts, user tags, and much more.

2. What are REST APIs used for?

One of the main benefits of REST is that they offer a lot of flexibility, which allows you to do more with this API. Listed below are few examples of what REST API’s are suitable for:

  • Cloud services : REST is useful in cloud services because you would require to control how the URL is decoded to bind to a service through an API. Microservices and Cloud computing will indeed make RESTful API design the law of the future.

  • Web use : REST is not affixed to client-side technology, these APIs can be reached upon from a client-side web project, an IoT device, an iOS app, or a Windows Phone. You are able to create the structure for your organization without distressing about being caught to a particular client-side stack.

  • Cloud applications :REST APIs are useful in cloud applications as their calls are stateless. If something fails, stateless components can easily reorganize and scale to adjust load changes.

3. What is the difference between REST API & SOAP (Simple Object Access Protocol)?

REST refers to Representational State Transfer SOAP refers to Simple Object Access Protocol 
It defines standards but they need not be followed rigorously. It specifies standards that are meant to be sternly followed.
REST architecture can have SOAP protocol as part of the execution. SOAP does not use REST as it is a protocol.
REST is more flexible like a browser and does not depend on how the server is developed unless it follows the protocols required for starting communication. SOAP client is more tied to the server which is the same for desktop applications having rigid contracts.
REST supports data of several formats like XML, JSON, MIME, Text, etc. SOAP only supports XML transmission between the server and the client.
REST read requests can be cached/stored. SOAP reads are not cacheable.
REST uses URI to render the resource logic. SOAP uses service interfaces for uncovering the resource logic.
REST is quicker. SOAP is sluggish.
REST only inherits the security measures based on what protocol it uses for the application. Since SOAP is a protocol, it defines its own safety measures.
REST is commonly preferred by developers as it provides more maintainability and scalability. SOAP is not the first choice, but they are used in cases where higher reliability and transmission of status data is required.
REST is an architectural design method for creating web services SOAP is a protocol used to execute web services.

Same rule applies when answering Rest API interview questions that focus on differentiating between two different products or application programming interfaces. Cite at least two differences, keep the points under two sentences and be to the point as much as possible.

4. List down HTTP methods supported by REST.

  • GET: It asks for a resource at the request URL. It should not contain a request body as it will be rejected. It can be kept on the server or locally.
  • PUT: , It updates the resource at the request URL
  • POST: It should return the modified or new resource; It submits information to the service for processing;
  • OPTIONS: It specifies which techniques are supported
  • DELETE: It deletes the resource at the request URL
  • HEAD: It delivers meta information about the request URL 

REST HTTP Methods are one of the most important concepts that a candidate should be aware of and recruiters like to ask these to the candidates as Rest API Interview questions to gauge their fundamental knowledge.

5. What is Web API? Give examples.

You may get asked a few Web API questions, including its meaning, examples, comparison, etc. While Rest API interview questions are a subset of the web api questions, it bodes well for a candidate to prepare for generic questions like these while appearing for a REST API focused interview.

Let us look at its meaning first. Web API is a framework, open-source that is used to write HTTP APIs. It denotes an API over the internet which can be retrieved using the HTTP protocol. It is significant to note that it is not a technology, it is a concept. Using a wide range of tools such as Java, and .NET, among others, developers can build Web API. Web API implements protocol descriptions and thus it integrates concepts like versioning, URIs, caching, request/response headers, and several content formats in it.

Examples of Web APIs

Google APIs –Their APIs include YouTube API, Blogger API, Google Analytics API, and Google Font API, among others.

Other than Google APIs, there are other social media APIs such as Scoop.it API, Facebook APIs, Twitter API, and LinkedIn API.

Same drill as other Rest API interview questions or web api questions – short description of two or more examples.

6. What are the key advantages of Web API?

The main advantages of using Web API are:

  • Self-Hosting
  • Content Negotiation
  • Filters
  • OData
  • Model Bindings
  • Routing

7. List the top three development and testing tools for REST API, along with their pros and cons.

Note: This is one of many usage-driven Rest api interview questions. The interviewer here not only wants to see how many tools the candidate has knowledge of, but also checks if the tools that the applicant is aware of are market-centric or not. Having working knowledge of a couple of testing tools for REST API concepts and Web API in general is considered a big advantage in these interviews. This answer provides an example way of answering these sort of Rest api interview questions.

Rest-assured: REST-assured is supposedly one of the best tools for testing APIs in Java. It is an open-source platform with a Java-specific language. The Rest-assured API was created so that there is no need to be an expert to test web APIs in HTTP.


  • There is no need to be an HTTP expert.
  • There is no need to code things from scratch as it comes with some integral functions.
  • It supports the syntax of BDD (Behavior Driven Development) testing –When/Then/Given.


  • It doesn’t support anything but Java.
  • It does not support SOAP APIs openly.

Postman: The next API testing tool, after REST-assured, is Postman. It offers a desktop app as well as a web version and can be used for testing API services. It allows the user to easily disseminate the knowledge with the team.


  • This tool is easy to use in comparison to others.
  • Easy to establish parameters on method calls.
  • Ability to store commands.
  • It does offer API development competencies as well.


  • Cost for enterprise is high.
  • The Enterprise version is easy to set up and use, but the number of requests is restricted.
  • Only one test can be done at a time. 

Katalon Studio : Katalon Studio is a free API testing tool for Desktop App, Web, and Mobile applications. It provides easy development by containing all plugins and frameworks in one package. It is suitable for experts as well as beginners, with the Manual and Scripting modes.


  • Katalon supports SOAP and RESTful requests.
  • It can be used for examining and automated testing.
  • It supports CI/CD (continuous integration and continuous deployment) integration.
  • It is a complete framework.


  • It is hard to troubleshoot issues.
  • It is difficult to debug code, and there are no compile-time error checks.
  • It does not have any support for distributed testing.

Point to note here that like examples, pros and cons of tools as answers to Rest API interview questions should be to the point and must not contain any fluff.

In conclusion, Rest API interview questions and concepts outlined here should provide a baseline for someone preparing for web api focused interviews. With microservices the preferred choice among websites and cloud service providers, REST API has gained tremendous traction in the past few years. As a result the open positions for skilled workers have skyrocketed. A combination of these Rest API interview questions, alongside hands-on knowledge of the basics should prepare a candidate enough ammunition to ace these interviews.

More Resources : part time jobs in Mumbai | part time jobs in Pune | team leader interview questions | ips interview questions

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