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Table of contents
1.
Introduction
2.
Beginner-Level REST API Interview Questions
2.1.
1. What does REST stand for? 
2.2.
2. What is REST? 
2.3.
3. What are the commonly used methods in a REST API? 
2.4.
4. What are RESTful APIs? 
2.5.
5. What are resources in REST? 
2.6.
6. What is URI? 
2.7.
7. What is the GET method in REST? 
2.8.
8. What is the POST method in REST? 
2.9.
9. What is the PUT method in REST? 
2.10.
10. Can the GET method be used instead of the PUT method in REST?
3.
Intermediate-Level REST API Interview Questions
3.1.
11. What are the critical characteristics of REST? 
3.2.
12. What markup languages can be used in a RESTful web API? 
3.3.
13. How is JAXB related to RESTful web API? 
3.4.
14. What are the tools used for testing and developing web API?  
3.5.
15. What is SOAP? 
3.6.
16. What are JAX-WS and JAX-RS? 
3.7.
17. What is the architectural style for creating a web API? 
3.8.
18. What are the features of a RESTful web API? 
3.9.
19. What is the statelessness of a server? 
3.10.
20. What are the most commonly used status codes in a web API? 
4.
Advanced-Level REST API Interview Questions
4.1.
21. What are the disadvantages of using RESTful web API? 
4.2.
22. What are some of the best practices while developing a RESTful web API? 
4.3.
23. What are Idempotent methods? 
4.4.
24. What are the core components of an HTTP Request? 
4.5.
25. What are the core components of an HTTP Response? 
4.6.
26. Define RestTemplate in Spring.
4.7.
27. What is HTTP Basic Authentication?
4.8.
28. How are REST APIs kept secure?
4.9.
29. Describe the payload.
4.10.
30. How are APIs tested?
5.
Frequently Asked Questions
5.1.
How do I prepare for REST API interview?
5.2.
How do you explain REST API in an interview?
5.3.
What are the 3 components of a RESTful API?
5.4.
What are REST APIs interview questions?
6.
Conclusion
Last Updated: Jun 12, 2024
Easy

Top REST API Interview Questions and Answers (2023)

Introduction

REST is the acronym for Representational State Transfer. REST is a software architectural design used to create a guide to the development and design of the architecture for the WWW(World Wide Web). It is used to define a set of constraints to be followed by the developer while designing a web application. REST is one of the most commonly asked topics in a technical interview or a viva. 

rest api interview questions

Here is the set of the top thirty REST API interview questions. We will also be looking at the solutions for these REST API interview questions.

Beginner-Level REST API Interview Questions

1. What does REST stand for? 

REST is the acronym for Representational State Transfer.

2. What is REST? 

REST is a software architectural design used to create a guide to the development and design of the architecture for the WWW(World Wide Web). It is used to define a set of constraints to be followed by the developer while designing a web application.

3. What are the commonly used methods in a REST API? 

The most commonly used methods in a REST API are,

  • PUT
     
  • GET
     
  • DELETE
     
  • POST
     
  • OPTIONS
     
  • HEAD

4. What are RESTful APIs? 

RESTful APIs or Representational State Transfer APIs, are a set of architectural guidelines for creating web services that allow users to interact with resources online. They place a strong emphasis on statelessness, which requires that each request include all pertinent data. This encourages scalability and makes server maintenance easier. RESTful APIs use a client-server design, which enables independent client and server component growth.

RESTFUL APIs provide a standardized interface and often employ standard HTTP techniques, which makes interactions constant and predictable. Through specific URLs, resources—which can be data or objects—can be accessed. Because of its simplicity, scalability, and interoperability with a wide range of programming languages and platforms, REST APIs are frequently used to create online applications and services.

5. What are resources in REST? 

In a REST architecture, every content is treated as a resource. The resources can be text files, HTML pages, images, videos, or dynamic data. The client can easily access and modify the resources in a REST architecture.

6. What is URI? 

A URI, or Uniform Resource Identifier, is a short collection of characters that is used to identify and find resources on the internet or inside of a network. Users and apps can access files, web pages, and other online material thanks to URIs, which act as distinctive addresses for resources.
When identifying resources, URNs (Uniform Resource Names) offer a permanent and location-independent identity (for example, urn:isbn:0451450523 for a particular book). Within the World Wide online, URIs are essential for linking, data retrieval, and online navigation.

7. What is the GET method in REST? 

The GET method, one of the standard HTTP methods, is used in REST (Representational State Transfer) to retrieve data or resources from a server. The server is instructed to fetch and return the requested resource, often in the form of an HTTP response, when a client sends a GET request to a particular URI (Uniform Resource Identifier). GET requests are safe and idempotent, they shouldn't have any negative impacts on the server or the resource being accessed.

8. What is the POST method in REST? 

The POST method is one of the common HTTP methods used in REST (Representational State Transfer) to create or submit data to a server. The server is told to process and save the data contained in the request body when a client sends a POST request to a certain URI (Uniform Resource Identifier). 

It is frequently used for operations that lead to the generation or alteration of data, such as submitting forms, uploading files, or performing updates via RESTful APIs.

9. What is the PUT method in REST? 

The PUT method updates the resources that are already available on the web server. The PUT method replaces everything at the target URL with the provided resource. The PUT method can be used to make a new resource or update an existing one. 

10. Can the GET method be used instead of the PUT method in REST?

No, it is not recommended to use the GET method instead of the PUT method. The GET method only has view rights, whereas the PUT method also has update rights. Use the PUT method to express the changes you want to make to a resource if you want to update or modify it using REST. The GET method should not be used to change or modify any data; it is only intended for data retrieval.

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Intermediate-Level REST API Interview Questions

11. What are the critical characteristics of REST? 

The critical characteristics of REST are,

  • We cannot start the server between two calls in a well-defined REST API.
     
  • The REST uses the GET method to access the resources, whereas Web Services use the POST method to make operations.
     
  • REST is stateless. Stateless means that the REST API server has no session data.

12. What markup languages can be used in a RESTful web API? 

JSON(JavaScript Object Notation) and XML(Extensible Markup Language) are the two languages that are used for creating a RESTful web API. Markup languages are often not used directly to represent data in a RESTful web API. Instead, structured formats like XML and JSON (JavaScript Object Notation) are used often to exchange data. These formats are suitable for data serialization and deserialization in HTTP requests and responses because they are small and easily accessible by humans. 
 

13. How is JAXB related to RESTful web API? 

In terms of data serialization and deserialization, JAXB (Java Architecture for XML Binding) and RESTful web APIs are connected. XML documents can be mapped to Java objects and vice versa using JAXB, a Java technology. Although JAXB is not specifically REST, it can be used with RESTful web services to process XML data.
 

14. What are the tools used for testing and developing web API?  

We can use the following tools for testing a RESTful web API,

  • Spring REST
     
  • Axis
     
  • CXF
     
  • Jersey API
     
  • Restlet

15. What is SOAP? 

SOAP (Simple Object Access mechanism) is a mechanism is used to exchange structured data while creating web services. It is renowned for its tight standards and robust typing and employs XML as its communication format, making it appropriate for enterprise-level applications. Through the use of SOAP, several systems can communicate with one another over a network in order to call methods and exchange data in a platform- and language-neutral fashion.
 

16. What are JAX-WS and JAX-RS? 

Java technologies for creating web services include JAX-WS (Java API for XML Web Services) and JAX-RS (Java API for RESTful Web Services):

JAX-WS: It concentrates on building web services that are SOAP-based and enables Java applications to communicate via the SOAP protocol.

JAX-RS: With the use of HTTP methods like GET, POST, PUT, and DELETE, Java programs may construct and use RESTful web services.
 

17. What is the architectural style for creating a web API? 

The architectural style for creating a web API is,

  • HTTP is used for the client and server communication
     
  • XML or JSON is used as the formatting or markup language
     
  • Simple URI are preferred as the address for the web services
     
  • The server has a stateless communication

18. What are the features of a RESTful web API? 

The features of using a RESTful web API are,

  • The RESTful APIs are based on the client-server model
     
  • REST uses HTTP(HyperText Transfer Protocol) for the communication
     
  • Resources can be easily accessed with the help of URI
     
  • REST follows the concept of a stateless server
     
  • REST can use a cache to minimize the number of server calls

19. What is the statelessness of a server? 

Statelessness of a server, often known as "statelessness" in the context of web applications and RESTful services, refers to the server's inability to retain any context or data on past interactions or requests from clients. Each client request is handled independently, and the server doesn't keep track of previous requests in its memory.
 

20. What are the most commonly used status codes in a web API? 

The most common status codes in a web API are,

  • 200 - Success
     
  • 201 - Created
     
  • 304 - Not Modified
     
  • 400 - Bad Request
     
  • 401 - Not Authorized
     
  • 404 - Not Found
     
  • 500 - Integral Server Error
     
  • 502 - Bad Gateway

Advanced-Level REST API Interview Questions

21. What are the disadvantages of using RESTful web API? 

The disadvantages of using RESTful web services are,

  • Since the RESTful web services follow statelessness, it is almost impossible to maintain sessions.
     
  • We cannot impose security restrictions in REST. REST can only inherit the security restrictions imposed by the protocols implemented.

22. What are some of the best practices while developing a RESTful web API? 

Some of the best practices to follow while developing a RESTful web API are,

  • It is always recommended to use JSON data format as much as possible while creating a RESTful web API.
     
  • The user should name the resource endpoints as plural nouns and not verbs.
     
  • The user should return appropriate error messages in case an error is encountered.
     
  • If the user is working with huge resource data, it is recommended to use the concepts of filtering and pagination.
     
  • The user is advised to use the cache feature provided by REST to enhance the user experience.
     
  • The user should ensure good security practices to make the API secure.

23. What are Idempotent methods? 

The Idempotent methods ensure that if a single request is called multiple times, the response should be the same for all the calls. While developing a REST API, it is always recommended to make the API Idempotent to ensure consistency in the API. They are HTTP methods that, when called repeatedly with the identical input parameters, yield the same outcome. In other words, repeated idempotent operations should have the same result as a single idempotent operation.
 

24. What are the core components of an HTTP Request? 

There are five main components of any HTTP Request,

  • Method: The developer needs the action to be performed. The developer can choose any of the methods, for example, GET, POST, PUT, etc.
     
  • URI: This part is used to identify the resource on the server.
     
  • HTTP Version: This part is used to specify the HTTP protocol version used.
     
  • Request Header: This part contains all the required metadata for the request message.
     
  • Request Body: This part contains the message to be passed to the server.
     

25. What are the core components of an HTTP Response? 

There are four main components of any HTTP Response,

  • Response Status Code: This part contains the status code for the requested server.
     
  • HTTP Version: This part is used to specify the HTTP protocol version used.
     
  • Response Header: This part contains all the required metadata for the response message.
     
  • Response Body: This part contains the message to be passed to the client.

26. Define RestTemplate in Spring.

The basic class providing client-side access to Spring-based RESTful services is RestTemplate. The REST restrictions are used to communicate with the server. This is similar to other template classes offered by Spring, such as JdbcTemplate and HibernateTemplate. The RestTemplate provides high-level implementation details for HTTP Methods such as GET, POST, PUT, and others and allows them to communicate using the URI template, URI path params, request/response types, request object, and so on as arguments.

27. What is HTTP Basic Authentication?

When using Basic Authentication as part of APIs, the user must submit the username and password, which are then concatenated by the browser in the form "username: password" and then base64 encoded. On every HTTP request from the browser, the encoded value is delivered as the value for the "Authorization" header. Since the credentials are just encoded, it is recommended to use this form when sending HTTPS requests because they are not secure and can be intercepted by anybody if security protocols are not utilized.

28. How are REST APIs kept secure?

In URIs, sensitive information such as a user id, password, or verification token should not be displayed. REST APIs can be kept secure by using security measures such as authorization and authorization, API server confirmation, TLs/SSL encryption, rate-limiting for DDoS assaults, and others.

29. Describe the payload.

The term "payload" in GET or POST requests refers to data in the HTTP response and/or response messages. For example, if you ask the Twitter API for a specific tweet, the payload will include the document describing the tweet's text as well as any files required to embed the tweet on a website. The POST method can also be used to include the payload of an HTTP request. When utilizing Twitter's API, the payload is the tweet text that you provide in the POST request.

30. How are APIs tested?

JMeter, Katalon, and PostmanStudio are among the software tools that can be used to test RESTful APIs. Sending several calls from the testing tool and observing how your API responds are frequent tasks in the testing process. Because of the automated testing capabilities provided by various testing solutions, you may easily execute a variety of scenarios.

Frequently Asked Questions

How do I prepare for REST API interview?

You must understand the fundamentals of REST APIs and their implementation methods. Aside from that, you must understand the concept of statelessness and the various HTTP status codes. It is one of the most common REST API interview questions.

How do you explain REST API in an interview?

When asked about a REST API in an interview, you should be able to describe it as a set of architectural guidelines and limitations for developing web services that permit interaction with resources on the internet.

What are the 3 components of a RESTful API?

The three main components of REST API are Uniform Resource Identifiers, Methods, and HTTP Headers. The URL specifies the path to the resource. An HTTP method tells the server what it needs to do to the resource. Headers are the metadata exchanged between the client and server.

What are REST APIs interview questions?

Some REST API interview questions include: what is REST API, what its features are, and what is addressed in RESTful web services. One of the most frequently asked questions is what the difference is between API and REST API.

Conclusion

This blog contained a series of frequently asked REST API interview questions. The blog also has sweet and to-the-point answers for the above-discussed REST API interview questions.

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