Rest API Interview Questions

Rest API Interview Questions: Rest API (Representational State Transfer Application Programming Interface) is a widely used architectural style for designing web services that communicate over the internet. Rest APIs allow software applications to interact with each other using standard HTTP methods such as GET, POST, PUT, DELETE, etc.

As Rest API has become an integral part of modern web development, it’s essential to have a solid understanding of Rest API concepts, principles, and best practices. During an interview, hiring managers may ask several Rest API interview questions to assess the candidate’s expertise and experience in Rest API development.

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Rest API interview questions can range from basic concepts such as HTTP methods, status codes, and headers to more advanced topics like security, performance optimization, and API design principles. Being well-prepared for Rest API interview questions can help you showcase your expertise and land your desired job in the field of software development. This article will provide a list of common Rest API interview questions and their answers to help you prepare and increase your chances of success.

Rest Assured API Testing Interview Questions

  • What is the difference between the patch and put method in RestApi?
  • When we use the get method, data is not secured, and when we use it to post, this method hides data.
  • What is Authentication?
  • Why do we use mocks or stubs?
  • What is the difference between rest API and microservices?
  • Why do we get parameter session and variable declaration in API?
  • What are the main methods that we use for API automation?
  • What are the JSON converters headers of API?
  • Once the response comes, what actually do we get?
  • How to create API?
  • How does caching work in microservices?
  • What is REST ASSURED?
  • Explain mocking.
  • What expectations does the Technical panel see for the tester from an API Automation perspective?
  • Why do we do API Testing what is the advantage and where we can do API testing?
  • Can anybody explain POJO
  • What are web services and APIs, and what are their differences?
  • What are the Authenticated techniques/Types? can we use them to access the rest of the API?
  • What are the different ways to pass authentication in API requests?
  • Difference between PUTS and POST in API.
  • What is the global variable in Postman?
  • Environment variable in postman.
  • Difference between put and patch.
  • What is the 409 response code?
  • How to pass JSON file to a payload
  • Pass payload using a hashmap.
  • Write a program to take a get request using rest assured, and from the response, verify if data is present in the database using SQL.
  • What is OUTH, and why does the company use it nowadays?

Rest API Interview Questions

Rest API interview questions assess a candidate’s knowledge and experience in designing and developing Rest APIs, covering HTTP methods, security, performance optimization, and API design principles. Preparing for these questions is crucial for candidates looking to succeed in software development job interviews.

  • What are Web services?
  • What is the difference between SOAP and REST
  • What is REST API
  • What is the difference between Web services testing and API testing
  • Difference between XML and HTML
  • What is Assertion
  • Types of Assertions
  • Difference between Xpath and XQuery
  • Types of Properties and their syntaxes
  • What is Data-Driven Testing
  • What is the Data Source Test step
  • Explain about JDBC process
  • How to Connect JDBC to SOAP UI
  • What is Connection String in JDBC
  • Difference between SOAP UI FREE v/s SOAP UI PRO
  • What are Data Sink and Data gen test steps in SoapUI pro
  • How to Transfer value using Property Transfer
  • What are Mock services
  • How to do Service mocking
  • What is the process of SOAP UI Testing
  • What is WSDL
  • What are the parameters are in WSDL
  • Explore the WSDL
  • Is WSDL necessary for SOAP UI?
  • Difference between HTTP and HTTPS
  • Why HTTP is important in Webservices
  • What is an Endpoint?
  • What are the HTTP methods and HTTP Status Codes?
  • Explain different types of HTTP methods and Usage
  • Explain different Status codes
  • Types of HTTP Status codes
  • What is the Request Header ? and its format?
  • What is Response Header ? and Its format?
  • What tools are available for SOAP testing
  • Do you have experience in Load Testing
  • How to test Load Testing
  • What are TPS, Response Time, and Breakeven point
  • Absolute vs. Relative Xpath?
  • What are Name Space and its usage
  • How to write Xpath for access attributes?
  • SOAP UI Architecture
  • How to generate Reports in the Free Version

Interview Questions on Rest API

  • Different HTTP methods
  • HTTP status codes ( 200/400/500 series)
  • Put/post/patch
  • 401 vs. 403
  • Query and path parameters
  • How to construct JSON requests (POJO/JSON Object/JSON Arrays)
  • How to validate Response ( POJO / JSON path /object Mapper)
  • How to validate/test API(different cases )
  • What are Authorization or API keys
  • RestAssured code snippets or HTTP client code snippets

Rest Assured API Testing Interview Questions

  • Difference between REST and SOAPUI.
  • The method in REST.
  • Difference between PUT and PATCH call
  • How to integrate postman into the project?
  • How will you handle dynamic payloads in API?
  • How do you capture specific response values and pass them to other requests?
  • What challenges did you face in API testing?
  • What is the difference between Authorization and Authentication?
  • What are the API status codes you have come across?
  • What is the difference between OAuth1.0 and OAuth2.O? When and where do you use and how. Can you write a sample code?
  • How do you get the response from one API and send it to another API?

Rest Assured Automation Interview Questions

  • What is Rest?
  • What tools are avail for REST?
  • What is JSON?
  • What is URI?
  • What is “R” in URI?
  • What are Params/Parameters?
  • What is HTTP?
  • Tell me a few HTTP methods and Status Codes.
  • What is the process for validating response data?
  • What Is the JSON path?
  • What is Header data?
  • What is an Authorization token?
  • What is the payload?
  • Steps to test REST application?
  • What is the usage of collections in POSTMAN?
  • What is WADL?
  • POST vs PUT

Rest API Testing Interview Questions

  • How will you handle server issues in API testing both in postman and, rest assured.. like 5xx.. explain
  • What is an API?
  • What’s the diff between Rest vs SOAP
  • What are the different HTTP methods?
  • What are the different status codes, and when will they occur?
  • What are the different ways you validate XML responses?
  • What are the different ways you validate the rest of the API response?
  • How do you use POJO? Sample POJO code for a JSON
  • How do you pass payload to rest API calls during automation?
  • Explain your automation framework.
  • Explain the challenges that you face during the automation of the rest APIs
  • What are the diff types of testing you do with an API
  • What is the diff between regular calls vs OAuth calls?
  • How do you test security testing using APIs
  • How do you do performance testing with APIs
  • What is the difference between Put vs Patch?
  • We have 200 APIs, and for all 200 APIs, there are seven fields..how you will validate. What will be your approach?
  • There are 25 fields you need to validate from the API response. What will be your approach? How will you validate? Will you create 25 variables to store responses for every field?
  • There are 1000 API post-request calls to create records. The best approach is to make our test cases run in any chrome version, irrespective of the chrome driver version.

Rest Assured Interview Questions

  • What is the RAML? What is the use?
  • How to handle dynamic bearer token authentication (token has changed every hour)
  • How do you know if your URL and query parameters, and path parameters are working or not
  • Where does use is given and when and then in your framework?
  • How to create a post request with dynamic data in your framework
  • Explain your framework
  • Rest and sop difference?
  • What does mean by rest is light compared to soap
  • Why soap is more secure than rest.
  • Different response code
  • When we get a stale element exception.
  • Explain overloading and overriding with examples.
  • Explain all the oops concepts you used in your framework.
  • If you cannot find any element, what techniques will you apply?
  • Verification and validation of different examples.
  • Response time in rest and soap services. Is any difference?

Rest Assured API Testing Interview Questions

  • Error code for authentication and Authorization
  • Whats authentication
  • What is the difference between put and patch requests?
  • Is there any way to verify the response on UI? It was asked in an interview after performing API testing how do you verify on UI.
  • How to debug/read/rewrite req/response of API over HTTPS using Charles?
  • What is the difference between oath 1 and oath 2?
  • Enlist some common tests that are performed on APIs?
  • How to identify oath 1 and oath 2?
  • What is the purpose of the oath?
  • Oath generation testing
  • When to use the post method
  • What patch method and when to use it
  • What are other tools for API testing, apart from postman
  • What all to think/consider for switching Automations framework
  • The internal and external API token
  • Generate Access token
  • What have mainly used HTTP methods other than post get put and delete
  • What have mainly used HTTP methods other than post get put and delete
  • How does basic Authorization work?
  • Explain in brief the different types of output observed of an API.
  • Can booleans parameterized
  • What all testing you will perform on an API
  • Whats SQL injection, how to do it
  • Explain in brief the different types of output observed of an API. – JSON, XML, HTML, text
  • Schema validation
  • Heartbeat call and logistics call
  • Https local map for Charles proxy

Rest Assured Interview Questions And Answers

  • What will you check first when a lot of failures in API automation?
  • What will you do when the API structure changes?
  • Which dependency is good to handle Json operations?
  • How do you keep Json requests in the automation framework?
  • Which of the following takes more time to script. Get or Post a call?
  • Tell me your approach to automating an API that is under development
  • Tell me a complex scenario you automated so far
  • What will be your action, when a mandatory header which is passed in all the services becomes optional?

Restassured Interview Questions

  • What is the difference between API and WebService?
  • What is the difference between SOAP & Rest API?
  • Can you write a sample of API(URL) and JSON?
  • How do you handle the Authentication token?
  • How many types of Authentication are in POSTMAN/ Rest-Assured.
  • What is the difference between OAuth1.0 and OAuth2.O, When and where do you use and how? Can you write a sample code?
  • What is the base URI in RestAssured?
  • Can you explain RequestSpecification request = RestAssured.given();
  • What will be returned type of response.jsonPath().getJsonObject(“XYZ”);
  • How do you extract the values of JSON and how do you validate the response.
  • Can you write a code for saving the response in a JSON file?
  • How do you validate the headers of the response?
  • What is the difference between Headers and Header classes?
  • What is difference between response.header(“xyz”) and response.headers() methods.
  • Can you extract all the headers from the response at run time?
  • What is JSONObject() , request.header(“xyz”), response.path(“lable”) , response.body().asString() , response.getBody().prettyPrint(); , RestAssured.given().queryParam(“xyz”,”abc”);
  • What is difference between request.get(“https//dev-mode.com/api/allcustomers”) and request.request(Method.GET,”/ allcustomers “);
  • What is the difference between PUT and Patch? Have you ever used and where.
  • What are status code(2xx ,3xx ,4xx, 5xx) in API.
  • How do you print your response in JSON format?
  • How do you post body in POST and how many ways to post.
  • What all are the dependencies for Rest-Assured.

Rest API Interview Questions For Experienced

  • How to parse a JSON
  • How to parse an XML
  • How to Insert key: value based upon some searching criteria
  • Write code for conversion of JSON to XML and XML to JSON
  • What do you mean by the query parameter and path parameter?
  • What is the difference between put and patch?
  • What is the validation while API automation?
  • Explain your framework(Rest Assured)
  • What do you mean by object notation and array notation in JSON?
  • Write code for JSON Read
  • What do you mean by POJO why do we use POJO?
  • What do you mean by authentication and what are the types of authentication while API testing
  • What is the difference between URI and URL
  • How do you store the result and use it further in groovy scripting
  • What do you mean by Test runner in groovy scripting
  • What is the Rest of the service architecture?
  • What is the soap service architecture?
  • What is the soap UI work hierarchy?
  • How to set and get property using Groovy scripting
  • What do you mean by jsonsluper and xmlholder
  • How to convert JSON to Hashmap
  • What do you mean by Data source Data Sink and Data Source loop and why do we use it
  • How to handle SSL in SoapUI
  • What are the different types of properties in SoapUI that you declare using Groovy scripting?
  • What is the main thing while API automation?
  • What do you mean by Webservices and why do we use Webservices.
  • What is the difference between soap and Rest?
  • What do you mean by UDDI .and what do you mean by WSDL.
  • What is the different type of HTTP Methods?
  • How to parse a list from a JSON, for example, there is JSON and there are multiple IDs how you will parse all the IDs from JSON and how you will parse a particular I’d from that JSON.

API Automation Testing Interview Questions

  • The model used of your Rest API means how your following rest API ( these are coming from the Richardson maturity model)
  • The architecture of the API project ( Jax-rs with jersey or restless etc)
  • How you create JSON data on post-call. ( I mean are you hardcoding data in code or somewhere you calling like JSON or CSV file)
  • How you extract path parameters
  • How do you read JSON response ( here JSON object, JSON array, reading whole key-value pair, etc)
  • The question will be about headers and cookies ( in Get call and post-call related)
  • Maintaining URLs ( means get a call or post-call or delete call URL; here interviewer will make twist based on your earlier told how your company follows API development, simply Richardson model)
  • Question will be from what is path parameters, query parameters, etc
  • Extent report or default report.
  • Some database query as you know API bit related to DB as just making the sure response and request was dropped in DB or not OK

Java Rest API Interview Questions

  • Difference between Get and Post call?
  • How/why do we call Get and Post a call?
  • Is it mandatory to send request data in JSON format only?
  • How does API work?
  • Please explain RPC API.
  • What is the difference between REST API and microservices?
  • Why we do get parameter session and variable declaration in API?
  • why do we use mocks or stubs?
  • Difference between SOAP API and REST API?
  • What is the difference between the patch and put method in RestApi?
  • What is the difference between a REST and RESTful?
  • What is REST ASSURED?
  • How does caching work in microservices?
  • What are the expectations the Technical panel sees for a tester from an API Automation perspective?
  • Why do we do API Testing what is the advantage and where we can do API testing?

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FAQ On Rest API

Here are the some of frequently asked Rest API Interview Questions.

What is REST API?

REST API is an acronym for Representational State Transfer. REST API provides a framework for designing network applications by using HTTP requests and responses.

It helps to build reliable and secure distributed systems that scale to meet the needs of large organizations while remaining simple enough for small teams or individuals to use them effectively.

It’s an architectural style that describes how resources are manipulated in the application using URIs (Uniform Resource Identifiers) and HTTP methods such as GET, POST, PUT, DELETE, etc.

Rest API Definition?

A REST API is a web application interface that provides access to data or functionality on one computer system via the network using standard, stateless HTTP requests.

The advantage of this method is that it can be used from any programming language, with any networking library.

It also allows developers to work with APIs without knowing how they are implemented or what they do.

What are Rest API best practices?

Rest API best practices are usually described as the following:

1. Take care of authentication, including basic authentication and token-based authentication.
2. Use different HTTP methods for different requests.
3. Put performance in mind when designing your API. You may need to use caching or compression depending on your needs.
4. Make sure you implement rate-limiting appropriately to avoid any security risks.

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