Top REST API Interview Questions

REST APIs are a widely used design style. Many tech companies expect software engineers to have experience in REST API and include questions on REST API in their tech interviews.

When preparing for a tech interview that requires knowledge of REST API, you must brush up on concepts such as REST API design principles, REST/RESTful web services, SOAP, JSON/XML/protocol buffers, and validation and persistence frameworks. To help you get started with your prep, we've collated some of the commonly asked REST API interview questions in this article.

Expert’s Quote: 

"RESTful APIs embody the principles of simplicity, scalability, and generality. They are not just a technology; they are a philosophy, enabling systems to evolve independently, promoting a decoupled and modular architecture that stands the test of time."

–Leonard Richardson

(author of "RESTful Web Services")

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In this article, we will cover:

• Basic REST API Interview Questions and Answers
• REST API Interview Questions for Experienced Developers
• REST API Interview Questions for Tech Leads
• FAQs About Rest API Interview Questions

Basic REST API Interview Questions and Answers

Here are a few REST API interview questions for beginners or freshers:

1. Define REST API with an example.

REST stands for Representational State Transfer, an architectural style for web services. REST API is an Application Programming Interface that conforms to the REST architecture. Like all APIs, REST API allows applications or devices to connect and communicate with each other.

For example, Twitter’s REST API allows developers to source tweets and other information from Twitter. Developers can also run a search query that will return the outcomes in JSON format.

2. What are some of the characteristics of REST?

Some of the key characteristics of REST are as follows:

• REST is stateless; hence SERVER has no session data.
• Every data is passed to the server; it gets restarted between two calls only if the REST API is applied.
• REST uses GET to access resources, whereas other web services use the POST method.

3. What are the features of RESTful web services?

The key features of RESTful web services are as follows:

• This web service is based on the Client-Server model.
• It uses HTTP protocol for fetching data, querying execution, and other functions.
• Through URIs, the web services get accessible resources.
• As REST API follows a stateless concept, client requests and responses are not dependent on others.
• Uses caching to minimize the repeated requests on server calls.
• RESTful web services also use SOAP services to implement REST architectural patterns protocols.

4. List the advantages and disadvantages of a REST API.

Advantages:

• REST is a lightweight protocol.
• Its methods can be tested on any browser.
• Since it works on HTTP Protocol, it is easier to learn.
• It supports many technologies for data transfer.
• There’s no strict contract between the server and the client

Disadvantages:

• Sessions cannot be maintained.
• As it works on HTTP, there is no chance of asynchronous calls.
• Since there’s no contract, the communication between the server and the client depends on emails or other documentation.

5. What is the optional architectural constraint on REST?

Code on Demand is the optional constraint of RESTful architecture. It allows the server to send executable codes to clients.

More Sample REST API Interview Questions (Basic Level)

1. Explain the HTTP request methods supported by REST.
2. What are the differences between PUT and POST methods?
3. Differentiate between AJAX and REST.
4. What are the practices to create a standard URI for a web service?
5. Distinguish between SOAP and REST.
6. Explain HTTP status codes.
7. What is a resource in RESTful services?
8. What is the purpose of URI in REST?
9. Explain the disadvantages of statelessness in RESTful web services.
10. What are the primary security issues of web services?

In the following sections, we’ll cover some advanced-level REST API interview questions.

Recommended Reading: Top Java Web Services Interview Questions You Should Prepare

REST API Interview Questions for Experienced Developers

Go through the following REST API interview questions if you are an experienced professional:

1. Describe the principles of the REST architectural style along with their benefits.

The REST architecture must follow five REST architectural constraints:

• Uniform interface accepts a standard single-language communication between the client and the server. It is beneficial for decoupling of client and server.
• Client-server model permits the client and server to operate and evolves separately. It also supports portability and scalability.
• Stateless protocol means the server will not store any information about the sessions. Thus it improves the performance by reducing the server load speed.
• Cacheable server responses are possible from clients' and intermediaries' ends. It also reduces client-server interactions hence supporting scalability and performance.
• Layered system between client and server has intermediaries like load balancers and proxy servers. However, these layers have different responsibilities but interact with each other. It also supports system scalability and security.

2. How does Microservice Architecture Work?

Microservice Architecture works in the following way:

• Various clients send requests from different devices.
• Identity providers then authenticate the client's identities and issue security tokens.
• API Gateway manages the client requests.
• Static content keeps all the content of the system.
• Management tool checks the balance of services on nodes and the failures as well.
• Service Discovery acts as a guide to find the route of communication between microservices.
• Content Delivery Networks are distributed network systems of proxy servers and data centers.
• Remote Services enable remote access information.

3. What are Options in REST APIs?

Options is an HTTP method that finds all the various HTTPS-supported options. This helps the clients decide which operations to use.

4. Explain Payloads.

This refers to the requested data presented in the body part of every HTTP request message. However, it is different from request parameters, and it can only pass through the POST method.

5. Define caching.

Caching is the process of storing server responses so they can be used whenever required.

Additional REST API Interview Questions for Experienced Developers

1. Differentiate between SOAP and REST.
2. How is AJAX different from REST?
3. What constitutes the core components of HTTP requests?
4. Define addressing in terms of RESTful web services.
5. Name some of the tools that can be used to develop or test RESTful services.
6. What are cache-control headers?
7. Explain JAX-RS.
8. What is Postman?
9. What are the uses of a Postman?
10. Describe the major security issues faced by web services.

Note that these advanced interview questions on REST API for experienced developers can also be helpful for freshers or early engineers.

Recommended Reading: Full Stack Developer Interview Questions

Behavioral Questions for REST API Interviews

When preparing for a REST API development interview, you should also consider behavioral interview questions. Here are a few commonly asked behavioral questions during a technical interview and how to answer them:

1. Tell me something interesting about yourself

You have to answer this question in such a manner that highlights your skills and achievements. However, do not brag.

2. Why are you interested in this role?

Check the job description and what the role requires. Frame your answer so that it illustrates your capabilities and career aspirations and how the role fits into that.

3. What influenced you to choose web development?

While you answer this question, always remember to be honest. You can also share any anecdotes that are related to your decision-making.

Additional Behavioral Questions for REST API Development Interviews

1. What are your goals as a tech lead?
2. Which programming languages are you comfortable in?
3. Are you comfortable in giving in-depth presentations?
4. How do you ensure work-life balance?
5. Are you working on any project in your spare time?
6. What IT helpdesk software are you familiar with?
7. How do you measure your team’s performance?
8. What measures will you follow to find qualified teammates?
9. Explain your research process when designing new software.
10. What is the first thing you would do as a Tech Lead?

Make sure to prepare for these REST API interview questions before your upcoming tech interview.

Recommended Reading: Why Do FAANG Interviews Need Dedicated Prep?

FAQs on REST API Interview Questions

Q1. Why do companies prefer a software developer who knows REST?

Trends like cloud computing and architecture based on micro-services are created by web services provided by REST API. It makes communication and computing easy for users. This is why tech companies prefer developers who know REST API.

Q2. What is REST API used for?

RESTful API is an architectural style that HTTP requests to access and use data that can be used for GET, PUT, POST, and DELETE data types. This refers to the reading, updating, creating, and deleting operations concerning resources.

Q3. What are REST API methods?

• GET: Retrieves information about the REST API resources
• POST: Creates REST API resources
• PUT: Updates REST API resources
• DELETE: Deletes REST API resources or any related component

Q4. What are the different types of API architectures other than REST?

• SOAP: Simple Object Access Protocol
• RPC: Remote Procedural Call

Q5. What is the difference between REST and RESTful APIs?

REST stands for Representational State Transfer, which is an architectural pattern that creates web services. While RESTful API implements that pattern.

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