If you’re interviewing for a Java Developer, Software Engineer, QA Engineer, or Network Engineer role, chances are you’ll be asked some REST API questions during your technical interview. And if you’ve interviewed for a job in tech before, you probably already know that practicing answering questions that might come up in your interview is a must.
One of the best ways to practice is to set up a mock interview. You can ask someone to help you out by playing the role of the interviewer and asking you questions that are likely to be asked during your interview. You can also do a mock interview on Zoom, which is a good idea if your real interview will be virtual. If you’d rather practice on your own, you can always record yourself answering questions and then play back the recording to see how you did.
To help you get ready for your interview, here are 15 common REST API interview questions, plus tips on how to answer them.
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1. What do REST and RESTful mean?
REpresentational State Transfer, often referred to as REST, is an architectural style that provides standards for computer systems on the web. And RESTful is an adjective used to describe the systems that are REST compliant. This type of architecture helps computers connected to the internet communicate using HTTP. They can do this directly with REST, similar to how web browsers and servers interact.
2. What are some of the primary attributes of REST?
REST architecture is defined by six constraints, which include:
- Client-Server: A model that dictates the separation of concerns between these two parties to ensure greater portability and scalability of systems.
- Uniform interface: A decoupling of the implementation and the services of components in the system.
- Stateless: All the information required to process a given resource is available within the request.
- Cacheable: Responses can be saved and reused for equivalent requests.
- Layered System: The system includes intermediaries.
- Code-on-demand (optional): Scripts can be transferred.
3. What are all the HTTP methods that REST supports?
REST supports the following HTTP methods:
- GET
- POST
- PUT
- DELETE
- OPTIONS
- HEAD
- PATCH
4. What are resources in the context of REST architecture?
Resources can be almost anything (typically some type of information) that can be represented digitally, and are identified by logical URLs.
5. Which markup languages are used within a RESTful API?
You can use XML and JSON with a RESTful API.
6. What is a markup language, and why does it matter in the context of REST?
A markup language is a method of annotating text that makes it readable and presentable by an application. Because a REST API can’t read all markup languages, you have to use either XML or JSON.
7. What tools do you need to test a web API?
Your answer to this question will depend on the tools you use and like, which may include SOAPUI, Postman, Katalon Studio, Apigee, Rest-assured, Airborne, and others.
8. What is the difference between PUT and POST?
Both of these methods transfer resources, but they have slightly different outcomes. A PUT is idempotent, which means multiple PUTs are equivalent to a single call. In other words, the resource will always be overwritten.
In contrast, multiple POSTs will create resources for each instance called.
9. Can you use a GET request as opposed to a PUT to make a resource?
No, you shouldn’t use PUT in place of GET, because a GET operation can only read or retrieve data, but PUT operations are used to create and/or update data.
10. What is SOAP?
SOAP stands for Simple Object Access Protocol, and it allows applications to transmit information using HTTP.
11. Which is faster, SOAP or REST?
This is a good question to bring up a past project where speed was your priority. You can explain how REST was the better choice for your project since it’s faster than SOAP.
12. Which is more versatile, REST or SOAP?
This is another question where you can discuss details from a past project in your answer. You can describe how REST is more versatile than SOAP since it supports more forms of data, and then discuss how that benefited your project. You may also want to mention that SOAP only allows you to use XML.
One thing to keep in mind when you’re asked questions focused on REST vs. SOAP is that in many cases, both can get the job done. For example, because REST tends to use less bandwidth than SOAP, you may want to opt to use it when bandwidth is at a premium — either for you or someone you’re communicating with, like a remote worker with limited internet service. But SOAP can be used if bandwidth isn’t a primary concern.
Another example is how REST might be preferred to SOAP because it doesn’t require you to rewrite a site from scratch. All you have to do is add more functionality.
Get ready for your REST API interview
Need a refresher on any of the concepts covered here? Check out our Connecting Front-End to Back-End course, where you’ll learn how to join the front-end and the back-end by creating REST APIs and using the MVC architecture. Our Create REST APIs with Spring and Java skill path also covers REST concepts, and you’ll finish the class having made an API of your own.
If you’re looking for more ways to prep for your interview, take a look at our complete guide to the technical interview, our tips on answering behavioral interview questions, and our advice for the whiteboard interview.
Our Career Center is packed full of additional interview resources, as well as job-hunting tips and advice.
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