Web API Interview Questions and Sample Answers

Web API Interview Questions


Application Programming Interface (API) is a term that refers to a set of protocols that allow. We will discuss Web API Interview Questions here. An API for the Web is referred to as a Web API. A Browser API can be used to expand the capabilities of a web browser. A web server’s features can be extended using a Server API. A web API can assist you in creating an AJAX-based ASP.NET program. A web API platform makes it simple to build services that can operate on a variety of entities. A web API could be accessed via the HTTP protocol through the internet. It’s a platform for creating and developing HTTP-based RESTFUL services. Different technologies, like java and ASP.NET, could be used to build the web API. A web browser and web server may use a web API. Regardless of the number of user applications that use it, an API will keep track of its core logic.

Consider the following scenario: There is a range of smartphone applications funded by various platforms and a web app. If no standardized web API exists, each client application would need its embedded enterprise logic to link directly to the server to extract, update, & modify information. As a result, making any changes to the client applications would be a lengthy process because each application must sync with the others. Furthermore, every upgrade will necessitate making improvements to each & every application separately. As a result, more work is required, more time and money is spent, and the app can contain numerous bugs and errors. As a result, using a central API to avail, update, or alter data is a safer option. It will be simple to manage the apps, and improvements will only have to be made once.

Why Do You Use a Web API?

When working with a native app that does not facilitate SOAP yet needs web, Web API apps are preferred over all other service providers. Web API services are indeed the best option for developing resource-oriented applications. Such services are developed using HTTP and RESTful services. Web API services are extremely useful if you want high performance as well as fast production of services. So, if you’re looking for support with Asp.net web app creation using Web API software, search for experts. We have started to experience creators at Capital in terms of extensive experience developing ASP.NET applications using cutting-edge technology and software. Contact us for a no-obligation quote & much more information about their services. Reasons why to choose Web API: 

  • Native Mobile Application Back End: ASP.NET Web API could be used as a backend for developing a native application for various devices that don’t recognize SOAP. ASP.NET Web API can be used as a backend of almost every native application that runs on a phone device apart from a Windows system. As a result, a web API is suitable for use with native apps that need Web API but not SOAP.

  • Create Web Applications That Use AJAX: The Asp.net API is an excellent option for creating client web apps that mainly focus on AJAX and don’t need as many configuration setups as WCF REST services.

  • Service Development Is Simple And Lightweight: To access a wider range of users, the Web API promotes the light architecture that powers HTTP services. Creating services with ASP.NET Web API is even easier and faster than with WCF.

As a result, Web APIs can be extremely useful in the creation of web applications, particularly ASP.NET web applications.

What are the best places to use the Web API?

  • Web APIs are extremely useful when creating RESTFUL web services with the.NET framework.
  • Web API aids in the advancement of HTTP services that communicate with client entities such as browsers, devices, and tablets.
  • Any app could use ASP.NET Web API, mostly with MVC.
  • A web API can aid in the development of AJAX-enabled ASP.NET applications.
  • As a result, web API enables developers to create ASP.NET apps consistent with virtually any browser and device.

How to use a Web API?

Web API accepts requests from various user devices such as mobile phones, laptops, and tablets & sends them to the web server, which processes them then returns the requested performance to the user. Web API refers to a system-to-system connection in which some other application can retrieve information from one server. The resulting data and output are displayed to the user after the implementation is completed. 

API gives its programmers access to data that is then made accessible to outside clients. When programmers choose to build a few of their information public, they “reveal endpoints,” which means they publish a part of the programming language they used to create their software. Other programmers will then use URLs or HTTP users to ask for information from those endpoints, allowing them to extract details throughout the app.

Server’s Perspective: 

A programmatic interface is a server-side web API. It is made up of one or more publicly accessible endpoints. It specifies a messaging system that sends and receives requests and responses. Mashup is a server-side API that mixes multiple server-side APIs into one web application. A webhook is a server-side API that accepts feedback in the form of a unique resource descriptor.

Client’s Perspective:

Client-side web APIs use JavaScript bindings that are widely used. Google built its native user architecture to substitute native plug-ins through stable native sandboxed interfaces & apps.

Steps to Use Web API 

  • The majority of APIs need an API key. Check for access specifications in the documentation when you’ve found an API you would like to try out. Most APIs would require you to verify your identity by signing in with a Google account. Whenever you open the API, you’ll be given a special string of figures & letters to access.
  • The most straightforward way to get started with an API is to look for an HTTP user online, such as REST-Client, Mailman, and Paw. These pre-built tools assist you in structuring your requests to access established APIs using the API keys you were given. You’ll still have to understand a few of the documentation’s syntaxes. However, coding expertise isn’t needed.
  • Creating a URL from current API documents will be the next effective way to get data from such an API.

Examples of common APIs include:

  • Google Maps APIs: The Google Maps APIs enable web designers to embed Google Maps into their pages via JavaScript and Flash functionality.

  • YouTube APIs: The YouTube API allows developers to incorporate YouTube usability into their websites and apps. Youtube APIs involve the YouTube Player APIs, another YouTube Information API. The YouTube streaming live API, several YouTube analytics API, and many others. 

  • The Flickr APIs: Designers are using the Flickr APIs to acquire information from the Flickr picture-sharing network.

  • Twitter APIs: Twitter gives 2 APIs, a REST API that enables developers to view core Twitter data and a search API that enables programmers to connect with Twitter search & trends information.

Features of Web APIs

  • Self-hosting and IIS hosting are also supported.
  • Can accept as well as generates non-object-oriented data such as photos, PDF files, and so on.
  • Supports a variety of text formats, including XML, JSON, and custom MediaTypeFormatters.
  • Accept header, as well as HTTP status code, are included in all feedback.
  • Supporting ASP.NET MVC functionality including routing, controls, action outcomes, filters, configuration binders, IOC containers, and dependency insertion
  • Since it uses HTTP commands, GET, POST, PUT, and DELETE, it promotes convention-based CRUD acts.
  • OData is automatically supported. Clients may use the framework for OData query creation by adding the [Queryable] parameter to a server method that responds to IQueryable.

What is the significance of the Web API?

A web API is a platform that essentially provides us with data and information through the database. Because of the below factors, it is important:

  • It’s used to give websites & user apps access to information via a user interface.
  • It could be used to retrieve and save information from a server
  • It accepts a variety of text formats, including XML, JSON, and others.
  • It works with any browser and any platform, including mobile, desktop, & web browsers.

5 Guidelines for Creating a Fantastic Web API

  • Documentation 

The documentation of the API method itself is reasonably simple, that is, requests or responses and explanations of each of the components in both. Certainly, a growing range of software applications is available to make the process of creating documentation easier and more effective. Users can also write something which analyzes their API, endpoints, as well as functions & creates documentation for themselves. However, the allocation of usage examples and, preferably, tutorials distinguishes excellent documentation from acceptable documentation. That’s what assists the user in comprehending their API or determining where to begin. It orients them and assists them in assimilating their API.

  • Stability & Consistency  

If you’ve already used Fb’s API, you’re well aware of how frequently their APIs are deprecated and rewritten. Theirs is not a developer-friendly viewpoint, never matter how well you admire their hacking culture and product. They are still widely popular because of their billion active customers, not because of their excellent API. However, you probably might not have the privilege of having such a large customer base as well as market share, so you’ll need a far less unstable API that can keep older versions working & maintained for several years. Perhaps even years. So, here’s a few pointers to get you started. 

  • Flexibility  

Most programmers are familiar with the phrase “garbage in, garbage out.” When introduced to web API architecture, this controlling principle appears to dictate a relatively strict approach to request validity. Isn’t that fantastic? There isn’t a mess, and there isn’t a problem. However, as with anything, there must be a balance. Since it’s impossible to foresee any scenario in which customers may choose to use the service, and because not some user platform is the same (– for example, not each platform has excellent JSON support, a strong OAuth library, respectively. ), it was a good idea to provide certain output & input restrictions versatility.

  • Security  

While security is clearly among the essential features to have in the web service, some developers find it extremely difficult to use. You can have functional instances about how to secure & approve when using your API, like the API operator. This must not be a daunting problem on which an end consumer spends hours. Make it a priority for them to either not even have to write some code and compose in far less than five minutes.

  • Ease Of Adoption

Here are some unique suggestions for making your API easier to use and adopt:

  • Ensure that your API is usable and that it functions for the first time, each time: Bring in new people. Start to use your API regularly to ensure that it isn’t frustrating in any manner you’ve been resistant to.

  • Maintain a straightforward approach. Don’t bother with complicated authentication: Don’t try to come up with some wacky URL scheme. Please don’t reinvent the wheel when it comes to SOAP, JSON, and REST. Use all of the methods which have already been introduced and are commonly recognized so that programmers need to know your API, not your API, plus ten mysterious technological advances.

  • Have language-specific libraries for your service’s GUI: Alpaca and Apache Thrift are two tools that can immediately create a library for users. Currently, JavaScript, PHP, Ruby, & Ruby are supported by Alpaca. Thrift supports C++, Java, PHP, Python, C#, Node, Delphi, OCaml, Smalltalk, Erlang, Cocoa, and other languages.

  • Make any necessary signups as simple as possible: If you’re not creating an open-source API, and if you have some signup method, ensure that customers are led to a guide as soon as they sign up. Also, render the signup procedure fully automated, so you don’t have to deal with people.

  • Have outstanding customer service: Lack of funding is a major impediment to adoption. What are your plans for handling and responding to a bug report? What about the paperwork that isn’t clear? Are you a novice user? Forums, bug tracking systems, & mailing help are all great places to start. However, make clear that if anyone reports a bug, you fix it. Nobody needs to come across a deserted forum or a long list of unresolved bugs.

Earning of Web API

In the United States, the average annual salary for an API Developer is $109,787 and $56.30 per hour. Starting salaries for entry-level jobs start at $72,925 annually, with the highest-paid employees earning up to $152,100 annually.

Web API Interview Questions

  • What exactly is a Web API?

Answer: As the name implies, a Web API (Application Programming Interface) is an API that can be accessed via the Internet using the HTTP protocol. It is widely regarded as the most effective medium for exposing or uncovering data and services to a variety of services. It’s a method for pushing information to the server that can also be reached by server code. It could be created or produced using a variety of technologies, including Java, ASP.NET, and others.

  • Why did you choose Web API?


  • It’s used to make basic HTTP Services that aren’t SOAP-based.
  • It’s also a simple way to create with Web API. REST Services powered by WCF
  • It’s built on HTTP and is simple to describe, expose, & ingest in a RESTful manner.
  • This has a light architecture that is suitable for devices with limited bandwidth, such as smartphones.
  • SOAP stands what? 

Answer: Web service communications use the SOAP message version, which is an XML message standard format. It supports HTTP and JMS as well as other transport protocols. It is also an XML-based messaging method of exchanging data among computer systems.

  • How do you restrict access to the Web API to a single HTTP verb?

Answer: A significant role is played by attribute programming. It’s simple to limit an ASP.NET Web API technique’s ability to be named using a specific HTTP method.

  • Is it possible to use Web API via an ASP.NET Web Page?

Answer: Yes, you can use ASP.Net web forms through Web API. It comes pre-installed with the ASP.NET MVC platform. It can, however, be utilized for the conjunction through an ASP.NET Web Format.

  • What is DelegatingHandler’s purpose?

Answer: Until routing, a Web API requires DelegatingHandler which displays Message Handlers.

  • What advantages does Web API have over WCF?


  • There is no need to specify or describe any additional config settings for different devices in Web API.
  • Since Web API uses various message formats like XML, it is simpler and better suited to lightweight services.
  • MVC functions are supported by Web API but not by WCF.
  • In comparison to WCF, Web API offers more vee service. Web API uses standard protection such as key authentication, simple authentication, & so on, while WCF utilizes the to offer safe service WS-I model.
  • Explain how MVC and Web API different.

Answer: The MVC architecture is used to create applications with a graphical user interface. Viewpoints can be used to create user interfaces in this case. Web API is a programming interface for creating HTTP services. To retrieve that data, certain apps may use the Web API methods.

  • Who can use Web API?

Answer: Any client that recognizes HTTP verbs like GET, PUT, Erase, and POST can use Web API. Web API services are simple to use by each customer because they don’t require any configuration. Infract, including mobile devices, such as smartphones and tablets, can quickly access Web API and is one of the technology’s most inherent benefits.

  • What are the benefits of using a Web API?


  • It has extra layers that essentially standardize interactions and provide various output as well as input format choices.
  • It works with ASP.NET MVC and a variety of web apps, including ASP.NET WebForms.
  • Web API tools are indeed the best for creating resource-oriented applications.
  • It also aids in the creation of RESTful & SOAP-based services.
  • What about the most popular return forms in Web API?

Answer: There is no clear data form for it. Based upon the company requirements, this could return information of any kind. Many HTTP forms, such as GET, POST, and PUT, will return information in various formats based on the use scenario.

  • What is the difference between XML and JSON?


  • XML: It is a markup language that allows you to express yourself in a variety of ways. It’s designed specifically for storing and transporting data. It’s comparable to HTML. However, it’s more versatile since users can make their customized tags. It’s used to describe structured data, including records, data, and configurations, among other things.
  • JSON: It’s a small file format for storing and transporting files. It’s a default message format for describing structured information based on JavaScript object syntax that’s easier to grasp. It is more convenient and quicker to use.
  • How do you deal with errors in a Web API?

Answer: In general, web APIs provide more flexibility when it comes to managing errors. Exception management is a programming method for dealing with run-time errors in software code. You can access, Exception detectors, report error filtration, or Exception controllers to manage errors. Exception handlers could be used to detect any uninitialized exception application-wide, whereas HttpResponseException could be used whenever an exception would be possible.

  • What are Exception filters in ASP.NET Web API?

Answer: A web API exception filter is usually used to manage certain unhandled exceptions. The IExceptionFilters interface is implemented. It is the simplest and most adaptable to use. 

Also read Java Design Pattern Interview Question To Prepare For

Web API Interview Questions and Sample Answers

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