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

Introduction

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!

Conclusion

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!