Best REST API Interview Questions To Ask A Developer

Hiring the right developer with a strong skillset in REST API can be a challenging task. One of the most critical parts of the recruiting process is the interview stage.

Asking the right questions during the interview can provide essential information about the candidate's knowledge and skills.

Here we have compiled the best REST API interview questions that can help you make an informed hiring decision.

1. What is your understanding of REST in Rest API?

This question is foundational and assesses whether a candidate understands REST's underlying principles.

A candidate should know that REST is an architectural style that defines certain constraints and properties, and is used to build web services that are lightweight, maintainable, and scalable.

Understanding of REST also includes knowing the concepts of resources, request/response model, statelessness, and cacheability.

2. Can you explain idempotent operations in Rest API?

This is an important concept that guarantees that no matter how many times a particular operation occurs, the outcome remains the same.

This is crucial in situations where a request may be repeated due to network issues or other errors, and it's necessary that repeated requests do not cause unwanted side effects.

3. What are Status Codes, and why are they important in REST API?

Understanding status codes is crucial for developers working with REST APIs. They provide information about the outcome of an HTTP operation, such as whether a request was successful, encountered errors, or requires further action.

Candidates who can explain status codes demonstrate their understanding of handling different scenarios and responses appropriately.

4. What's the difference between a PUT and a POST request?

PUT and POST are HTTP methods used for different purposes in REST APIs. Evaluating a candidate's comprehension of their distinctions helps determine their understanding of data manipulation in API interactions.

Knowing when to use PUT (updating a resource completely) or POST (submitting data for processing) ensures data integrity and consistency.

5. What are the best practices for structuring a RESTful URIs?

RESTful URIs play a significant role in making APIs intuitive and user-friendly.

Candidates should be familiar with best practices, such as using nouns instead of verbs, maintaining lowercase letters, using hyphens for readability, and ensuring secure communication through SSL.

This knowledge indicates their ability to design APIs that are easy to understand and work with.

6. What are the components of a RESTful Web Service?

RESTful Web Services have specific components that define their structure and functionality.

Candidates who can explain these components, including resources, request/response handling, status codes, and HTTP methods, demonstrate their understanding of building and maintaining RESTful APIs.

7. Can you explain how caching works in a REST API?

Caching is a technique used to store copies of frequently accessed data and serve it from the cache when requested. This reduces the load on servers and improves the performance of the application.

Candidates should be aware of when and how to use caching to optimize performance.

8. How would you handle versioning in a REST API?

Versioning is essential in REST APIs to manage changes while maintaining backward compatibility.

Candidates should be familiar with various versioning approaches, such as URI versioning, request header versioning, and media type versioning.

Understanding how to handle versioning demonstrates their ability to evolve APIs without disrupting existing clients.

9. What is HATEOAS, and why is it relevant in REST API?

HATEOAS is a key principle in REST that enriches the API's usability by providing hypermedia links dynamically.

Candidates who understand HATEOAS can explain how it enables clients to navigate and interact with the API effectively.

This knowledge showcases their understanding of building self-descriptive and discoverable APIs.

10. How do you test a REST API?

Candidates should have knowledge of testing techniques specific to REST APIs.

Functional testing, integration testing, load testing, and security testing are crucial aspects to ensure the API functions correctly and meets performance and security requirements.

Familiarity with tools like Postman, JMeter, and unit testing frameworks showcases their ability to validate and verify API functionality.

11. What are the methods or ‘verbs’ of REST API?

HTTP methods, also known as verbs, are the foundation of RESTful APIs.

Candidates should comprehend the purpose and appropriate usage of methods like GET, POST, PUT, PATCH, and DELETE.

Proficiency in using these methods ensures proper interaction with resources and adherence to REST principles.

12. Can you explain pagination in REST API?

Pagination is crucial when dealing with large data sets in APIs.

Candidates who can explain pagination understand the technique of dividing data into manageable chunks across multiple pages.

They should be familiar with concepts such as limit and offset, or cursor-based pagination, to efficiently navigate and retrieve data from APIs.

13. What are common security measures for REST APIs?

Security is a critical aspect of REST API development.

Candidates should be well-versed in common security measures such as authentication (e.g., OAuth or JWT), encryption, rate limiting, and input validation.

Understanding these measures demonstrates their awareness of potential vulnerabilities and their ability to implement robust security practices.

14. What are some challenges you faced while designing and using REST API and how did you overcome them?

REST API development can present various challenges, ranging from performance issues to scalability concerns or handling complex data structures.

By asking candidates about challenges they have encountered and how they overcame them, interviewers can gauge their problem-solving abilities, resourcefulness, and adaptability.

This question provides valuable insights into a candidate's practical experience and their approach to addressing real-world problems.

15. How do you keep up-to-date with the latest technology trends in REST API?

Keeping up with the latest technology trends is crucial for REST API developers.

By asking candidates how they stay up-to-date with the latest advancements, interviewers can assess their enthusiasm for continuous learning and their strategies for remaining informed.

Candidates who actively seek out new knowledge, attend conferences or webinars, follow industry blogs, or participate in relevant communities showcase their commitment to professional growth and their ability to adapt to emerging technologies.

Is there another way to assess REST API skills?

Now that we've identified these key interview questions, it’s important to note that evaluating a developer's skills should go beyond just straightforward questions. Assess their logical reasoning ability, their approach to tackling new challenges, and their ability to collaborate and communicate in your team's setting.

Pairing technical assessments, such as a REST API test, with these interview questions can give a more holistic view of the candidate’s abilities and potential for success in your particular organization.