rest api interview questions: 41 REST API interview Questions (With Examples and Tips)



REST API Interview Questions & Answers

REST APIs are a popular way to expose services, which makes them an important topic for any developer to know. Without an understanding of RESTful design principles, you’ll find it difficult to develop and publish RESTful APIs in any language. If you’re interviewing for a job that involves developing or maintaining a REST API, then it’s important for your interviewer to assess your knowledge about this subject first.

Here are 41 questions that will help you prepare:

-What is a RESTful API?

-Can you explain the difference between a RESTful and SOAP API?

-Which HTTP methods can be used to create, read, update and delete data from an API? How would you use each one?

-How do you scale a RESTful API using webhooks?

-What is the difference between POST, PUT and PATCH? Which one should you use for each situation? -How would you build a RESTful API using Spring Boot, Hibernate and PostgreSQL? -What’s the difference between HTTP status codes 200 (Success), 400 (Bad Request) and 500 (Internal Server Error)?

What is REST?

REST stands for Representational State Transfer. It’s an architectural style that defines how you can use HTTP to interact with web services. It’s not a protocol, standard, set of rules or framework. It’s also not a library that implements RESTful principles in your codebase like Spring does with HATEOAS (Hypermedia As The Engine Of Application State).

What are the advantages of using REST APIs?

There are several advantages of using REST APIs.

  • They’re easy to build and maintain. You can create new APIs at any time, and you do not have to change the existing application code when you make changes.
  • They’re easy to use. The client tools will handle most of the heavy lifting for you, leaving only simple tasks like authentication or authorization left for developers to implement themselves (if they choose).
  • They scale well because they don’t require much bandwidth or processing power from servers compared with SOAP-based web services that use XML messages over HTTP POSTs/GETs instead of JSON-based calls over HTTP GETs/PUSHes respectively; this makes them lightweight enough so that even mobile devices with limited processing power can access them without any problems whatsoever! In fact there are many companies out there today who rely solely on RESTful APIs provided by Open Source projects such as Apache Kafka or Elasticsearch which allows them in turn access data stored within those systems without having access rights granted directly by their owners – something which would never happen if we were only talking about traditional applications instead.”

Can you tell us about the RESTful design principles?

REST is a style of software architecture for distributed systems. It has been promoted by Roy Fielding in his 2000 doctoral dissertation and subsequently refined by him and others. The term REST was coined in 2007 by Dave Winer, who credited James Grenning with proposing it in 2004.[1]

The key design principles of REST are:

  • Client-server: A web server hosts application state at any given time, but clients can manipulate that state as well as retrieve it using hypertext requests over HTTP/S (or HTTPS). This means that there are no remote procedure calls (RPCs), just GET/POST requests sent back and forth between the client and server; this gives us an illusion of statelessness since each request can be seen as independent from previous ones even though each one might depend on information stored on either side before making its own decision about which piece(s) should be changed next time around — so long as we continue following these rules then we won’t run into problems later down line when trying something new like adding another step between two existing ones because those changes won’t break anything else already set up within our system!

How will you make API calls in PHP, Python and Java?

  • PHP
  • Python
  • Java

Does the size of an API matter for performance?

Yes, the size of an API matters for performance. A large API will take longer to load and process than a small one. It can also use more bandwidth and be harder to debug because there are more lines of code that need to be analyzed when something goes wrong.

How to pass data from server to client side in JavaScript API?

  • You can use JSONP to pass data from server to client side in JavaScript API.
  • JSONP is a cross-domain communication technique that uses a script tag, which is not supported by all browsers.

What is JSONP and why is it used?

JSONP (JSON with Padding) is a cross-domain communication technique that enables us to bypass the same origin policy. The JSONP technique allows us to send data from server to client side in JavaScript by providing a callback function name and passing it as an argument.

JSONP is not secure, since it’s possible that someone could change your JSON response and send you malicious code or data via their website. For example: You have an API endpoint that returns the following: {“firstName”:”John”,”lastName”:”Smith”} If I wanted my own code on my website/blog to access this information, I could call your API with something like http://examplewebsite/api/user?callback=myFunction That would force your server-side code into running whatever myFunction() returns instead of returning its original value!

This means if you’re using JSONP on your server side applications then make sure that only trusted people have access; otherwise it could lead them straight into trouble!

What are the different ways to handle errors while making API calls?

There are various ways to handle errors while making API calls.

  • Use try..catch blocks: In this approach, you can use a try..catch block to handle any exceptions that may occur during the execution of your code.
  • Use return codes: A return code is a response field in the HTTP header that indicates whether or not an operation was successful. If you are using RESTful APIs, then each request will have its own unique response code which tells us if it succeeded or failed. So when we receive any error from our server, we can simply check whether it has been returned as an error message through this method and act accordingly based on what we find out about our request status code (i.e., 200 OK).

How do you cache API requests using HTTP Headers in ASP.NET MVC Web API?

The HTTP Header is an optional field that you can use when you want to configure the request, response and cache behavior of your web API.

One common use case for caching is when a client needs to make multiple requests for data from your backend service. By using Cache-Control, no-cache directives in the header you can tell browsers not to cache any responses from your server and also specify how long they should store them before asking again.

How do we determine whether a POST request contains valid data or not? Section 7) How can we control who can access our services and APIs using CORS protocol and header restrictions in ASP.NET Core 2.1 Web API (MVC)?

CORS is a mechanism that prevents cross-origin HTTP requests from being made unless the server explicitly allows it. It’s used to prevent malicious JavaScript code from making cross-origin requests to a server.

CORS is supported in most modern browsers, but can be disabled if required. To enable CORS in ASP.NET Core 2.1 Web API (MVC), follow these steps:

  • Add the following line at the top of Startup class: public void ConfigureServices(IServiceCollection services) { ServicesConfiguration .EnableCors(); }

always keep in mind that Client needs to be able to trust your services

  • Always keep in mind that Client needs to be able to trust your services.
  • CORS requests: In order for clients to make cross-origin requests, the server must return an appropriate Access-Control-Allow-Origin header.
  • Error responses: If a resource cannot be found or is not valid, then send back an appropriate response code (404), along with any additional information that might help the client fix their issue.
  • Invalid data: If a request contains invalid data (e.g., malformed JSON), then send back an appropriate status code (400) along with any additional details about what went wrong so the client can make corrections before sending another request.
  • Security issues: If someone tries accessing sensitive information without proper authorization, then respond appropriately by sending back either a 401 Unauthorized response or 403 Forbidden response depending on what level of access they have been granted previously by making use of HTTP Basic Authentication or OAuth2 bearer tokens; if none was available then simply deny access altogether because no one should ever know how many times I’ve watched “The Office” TV show since season 7 premiered last year!


We hope this article has helped you learn more about REST APIs and how they can be used. If you’re looking for more information on this topic, check out our other articles on the subject!

Answer ( 1 )


    Are you preparing for a job interview that involves REST API? Do you want to know the most common questions and tips that can help you ace the interview? Look no further! In this article, we will cover 41 of the most frequently asked REST API interview questions with examples and practical tips. Whether you are a beginner or an experienced developer, these questions and answers will give you an edge in your next REST API job interview. So let’s dive into the world of REST APIs and get ready to impress your interviewer!

    What is a REST API?

    REST API stands for Representational State Transfer Application Programming Interface. It is a web protocol that allows different applications or systems to exchange data over the internet in a standardized way. RESTful APIs use HTTP requests to GET, POST, PUT and DELETE data.

    One key feature of REST API is its statelessness nature, meaning each request from the client contains all necessary information needed by the server to handle it without requiring any context or session information stored on either side.

    REST API has become popular due to its simplicity and scalability, which makes it easy for developers across multiple platforms and languages to interact with each other’s application programmatically.

    Moreover, unlike SOAP (Simple Object Access Protocol), which requires XML-based messages sent via HTTP/SMTP protocols between clients and servers, REST uses JSON format payload that can be used with any programming language supporting HTTP verbs such as Java or Python.

    In summary, a REST API provides an architectural style for creating lightweight scalable web services that can easily integrate into various software applications using standard interfaces built on top of existing technologies like HTTP/HTTPS/TCP/IP protocols.

    Types of REST APIs

    There are primarily two types of REST APIs: public and private. Public APIs are those that can be accessed by anyone over the internet, while private APIs are internal to an organization or a company.

    Public APIs provide access to third-party developers who can use them to build applications that integrate with the API’s functionality. For instance, Facebook offers a public API that allows developers to build apps using their data.

    On the other hand, Private APIs are used within organizations for internal communication between different systems and services. These APIs require authentication before they allow access, which ensures security and confidentiality.

    Moreover, there are also commercial REST APIs – these could either be public or private but come at a cost. Commercial REST API providers offer additional functionalities such as support and maintenance in exchange for fees paid by users of their service.

    Understanding the difference between various types of REST APIs is essential when designing one for your organization or building an application using external Restful services offered publicly online

    Architectural Constraints of REST APIs

    REST APIs are based on a set of architectural constraints that govern their design and implementation. These constraints ensure that RESTful web services are scalable, reliable, and maintainable. The five key constraints of REST architecture are client-server, statelessness, cacheability, layered system, and uniform interface.

    The client-server constraint separates the concerns between the user interface (client) and data storage (server). This separation enables scalability by allowing both components to evolve independently. Statelessness means that each request from a client must contain all necessary information for the server to respond without relying on prior context.

    Cacheability involves servers responding with appropriate caching headers so clients can store responses locally. Layered systems enable intermediaries such as load balancers or proxies to be placed between clients and servers without changing either component’s behavior.

    Uniform interfaces provide a consistent way for clients to interact with resources across different services. By following these architectural constraints along with proper design practices, developers can create efficient and effective REST APIs capable of meeting diverse business needs.

    Designing a REST API

    Designing a REST API is a crucial step in building a successful web application. It requires careful consideration of the architectural constraints and best practices to ensure that your API is scalable, flexible and easy to use.

    One important aspect of designing a REST API is defining the resources that will be exposed through the API. Resources can be anything from user accounts to blog posts or products in an e-commerce platform. Each resource should have its own URI (Uniform Resource Identifier) so that it can be easily identified and accessed by clients.

    Another important aspect is choosing the appropriate HTTP methods for each resource. The most commonly used methods are GET, POST, PUT and DELETE but there are other less common ones such as PATCH or HEAD. These methods allow clients to perform different actions on resources such as retrieving data, creating new resources or updating existing ones.

    It’s also essential to define clear error messages that will be returned by the server when something goes wrong with an API request. This helps developers understand what went wrong and how they can fix it without having to dig into complex logs or documentation.

    Designing a REST API involves providing thorough documentation that clearly explains how each resource works, which parameters are required for each request and what responses they should expect back from the server.

    Designing a REST API requires attention to detail and adherence to best practices in order to create an efficient and effective interface between client applications and servers.

    Best Practices for Designing a REST API

    When designing a REST API, there are certain best practices that should be followed to ensure its efficiency and usability. Here are some of the most important ones:

    First, it’s crucial to choose clear and consistent naming conventions for your API endpoints. This will make it easier for developers to understand how the API works and how they can use it in their applications.

    Next, always use HTTP methods correctly when defining actions on resources. For example, GET should only be used for retrieving data while POST should be used for creating new resources.

    Another good practice is to keep your responses consistent by using standard response codes such as 200 (OK), 201 (Created), 400 (Bad Request), and so on. This will help prevent confusion among developers when interacting with your API.

    In addition, always provide detailed documentation of your REST API so that developers can easily understand how it works without having to rely on guesswork or trial-and-error.

    Security is key when designing a REST API. Always use secure communication protocols like HTTPS and implement authentication mechanisms such as OAuth2 or JWT tokens to protect against unauthorized access.

    By following these best practices, you’ll create an efficient and user-friendly REST API that meets the needs of both developers and end-users alike.

    Tips for Creating a REST API

    To wrap up, creating a REST API can be a complex task, but by following these tips and best practices, you can ensure that your API is efficient, scalable, and easy to use. Remember to keep the user experience in mind when designing your API and always document it thoroughly for developers who will be using it.

    By incorporating these guidelines into your development process, you’ll create a RESTful API that enables seamless data exchanges between systems or applications. So start implementing these tips today and take one step closer towards building an effective RESTful API!

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