Top 10 Web API Interview Questions & Answers [UPDATED 2024]

Before we go into what a Web API is, let’s define an API (Application Programming Interface).

According to Wikipedia, an application programming interface (API) is a set of subroutine definitions, protocols, and tools for developing software and applications in computer programming.

API is a type of interface that provides a collection of methods that let programmers access certain features or data of an application, operating system, or other services.

As the name implies, Web API is a web-based API that can be accessible over the HTTP protocol. It is an idea rather than a technique. We may create Web APIs utilizing a variety of technologies such as Java, NET, and others. Twitter’s REST APIs, for example, give programmatic access to read and write data, allowing us to incorporate Twitter’s features into our own application.

If you’re a Web API student or a professional working to improve your skills in this framework, you already understand the value of having a trustworthy source of Web API interview questions. Because the focus of Web API is on practical applications, any set of questions must address how Web API may be useful in real situations. These interview questions and answers might also help you in preparing for your ideal position in this sector.

It’s worth noting that all the following questions and answers have been hand-picked by experienced hiring managers with years of experience in the area. But, conducting further research to improve your readiness would be harmless.

Top 15 Web API Interview Questions & Answers In 2024

Tell me why is the Web API important?

Answer:  A web API is a service that essentially supplies us with information or data from the server. Because of the following reasons, it is critical:

• To offer a data access interface for websites and client applications.
• We use it to retrieve data from a database and save it back to it.
• It accepts a variety of text formats, including XML, JSON, and others.
• It works with every type of browser and any sort of device, including mobile, desktop, and online.
• It makes use of low-bandwidth data, such as XML or JSON, and is suitable for devices with limited bandwidth, such as smartphones.
• Web API is more appropriate for UI/UX, raises interest in the company’s goods and services, and boosts website traffic from a commercial standpoint.

What is Web API and why do we use it?

Answer: As we have mentioned above, a Web API (Application Programming Interface) is an API that is accessible over the Internet using the HTTP protocol. It is the most effective platform for disclosing or discovering data and services to a variety of services. It’s a mechanism for pushing data to a server that may also be accessible by server code. It may be created or developed using a variety of technologies, including Java, ASP.NET, and others.

Uses of the Web API:

• It has other layers that merely standardize communications and give various input and output formatting choices.
• It works with ASP.NET MVC and a variety of web applications, including ASP.NET WebForms.
• Web API services are the finest when it comes to creating resource-oriented services.
• It also aids in the development of RESTful and SOAP-based services.

What are some of the most common Web API return types?

Answer: To be super honest with you, there is no particular data type for it. Depending on the business requirement, it can return data of any form. Many HTTP methods, such as GET, POST, and PUT, can return data in a variety of forms, depending on the use case.

What is the difference between WCF and Web API?

Answer:

WCF: (Windows Communication Foundation) is a SOAP development framework (Service-oriented applications). This framework is useful for creating, configuring, and deploying network-distributed services, as well as implementing them.

Web API: is an application programming interface that may be useful by both web browsers and servers. Browser API merely adds to the capabilities of web browsers, whereas Server API adds to the capability of web servers.

Why choose Web API over WCF?

Answer:

The following are some of the reasons why Web API is better than WCF:

• Web APIs make advantage of all HTTP capabilities, including URIs, request/response headers, caching, versioning, and a variety of content types.
• In Web API, there is no need to create or explain any additional config settings for distinct devices.
• Because Web API supports a variety of text forms, including XML, it is quicker and more suitable for lightweight applications.
• Web API supports MVC features, but, MVC features do not.
• When compared to WCF, the Web API gives more freedom.
• To offer safe service, Web API employs standard security such as token authentication, basic authentication, and so on, whereas WCF uses the WS-I standard.

Mention the difference between REST API and RESTful API

Answer:

REST (Representation State Transfer) API: is an architectural approach that makes effective use of current web technologies and protocols. It is a collection of guidelines that developers must follow while creating scalable APIs or services. GET, DELETE, POST, and PUT are examples of HTTP verbs.

RESTful API: stands for “Resource-Oriented Service-Oriented Architecture.”

What are some of the benefits of utilizing Rest in a Web API?

Answer: Because of the following reasons, REST is highly significant and useful in Web API:

• It reduces the amount of data sent between the client and the server.
• It’s simple to use and light.
• It gives you additional options.
• It also handles and manages a variety of calls and returns data in a variety of forms.
• Recommended for usage in mobile apps since it reduces data transmission between the client and the server.
• Instead of using more sophisticated alternatives like CORBA, COM+, SOAP, or RPC, it employs basic HTTP calls for inter-machine communication.

Explain media type formatters.

Answer: Media type formatters are classes in the web API that are in charge of serializing data. Serialization, in this context, refers to the act of converting data into a format that can be transferred and afterward reconstructed. Web API may better comprehend request data format and provide data in the format that the client expects by serializing request/response data. An HTTP response or request simply defines the data sent between the client and the server.

What are Web API filters?

Answer: We use these Filters to add more logic to the Web API framework’s request processing at various levels. There are several sorts of Web API filters accessible, as shown below:

• Authentication Filter: It authenticates HTTP requests and manages authentication. It also aids in the verification of user information. It verifies the user’s identification.
• Authorization Filter: This filter deals with authorization. It takes place before the controller action. This filter determines whether or not a user has been authenticated. Unless the user has the green light, it will not call up the action and return HTTP status 401.
• AuthorizeAttribute: is a Web API-provided built-in authorization filter.
• Action Filter is a type of attribute that may be useful to individual controller actions or the whole controller. We utilize it to give additional logic before or after the operation of a controller. It’s just a technique to extend the capabilities of Web API services.
• Exception Filter: We use this filter to deal with unhandled exceptions in the Web API. When a controller action throws an unhandled exception that isn’t HttpResponseException. It will implement the interface “IExceptionFilter.”
• Override Filter: This filter’s job is to keep certain action methods or controllers out of the global or controller level filters. Its sole purpose is to change the behavior of other filters for specific action methods.

How do you deal with errors in a Web API?

Answer:  In general, web APIs offer more flexibility when it comes to managing failures. Exception handling is a programming method for dealing with run-time problems in application code. To deal with errors, you may utilize HttpResponseException, HttpError, Exception filters and handlers. An exception filter may be useful to identify unhandled exceptions on actions or controllers, handlers are useful to identify any sort of unhandled application-wide, and HttpResponseException can be useful when an exception is possible.

At the bottom line, it is important to mention that these questions along with answers are essential in every API interview. Carefully reading and understanding these Web API interview questions and answers will give you the chance to increase your possibilities in acing any Web API interview question. But the question that repeats itself is how to ideally prepare for any job interview?

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