REST API Interview Questions Every Developer Should Know

Are you gearing up for a developer interview and feeling nervous about the REST API section? You’re not alone! REST APIs are the backbone of modern applications, from social media to online shopping, making them a favorite topic in technical interviews. Whether you’re a beginner or a seasoned coder, mastering REST API concepts can help you shine. In this blog post, we’ll explore the most common REST API interview questions every developer should know, share practical tips, and equip you to answer with confidence. Let’s dive in and get you interview-ready!

What is REST and its Key Principles?

REST, or Representational State Transfer, is an architectural style for building networked applications, typically using HTTP. Interviewers ask this to test your core understanding. REST APIs rely on standard HTTP methods like GET, POST, PUT, and DELETE to manage resources identified by URLs.

• Key Principles: Statelessness (each request stands alone), client-server separation, uniform interface, and cacheability.
• Example: A GET request to /users/123 fetches user data without changing the server.

Pro tip: Highlight how REST’s simplicity and scalability make it perfect for web services. Explain why statelessness boosts scalability.

What are the Main HTTP Methods Used in REST APIs?

This question checks if you know how REST APIs perform actions on resources. HTTP methods define what you can do, and their roles are essential to understand.

• GET: Retrieves data (e.g., fetching a user profile).
• POST: Creates new resources (e.g., adding a user).
• PUT: Updates existing resources (e.g., editing user details).
• DELETE: Removes resources (e.g., deleting a post).

Fun fact: GET, PUT, and DELETE are idempotent—repeating them doesn’t change the result—but POST isn’t. Mentioning this shows you’ve gone beyond the basics.

What are HTTP Status Codes and Their Importance?

HTTP status codes tell you the result of an API request, and interviewers expect you to know the key ones. They’re vital for debugging and clear client-server communication.

• 200 OK: Request succeeded (e.g., data retrieved).
• 201 Created: Resource created successfully.
• 400 Bad Request: Invalid request syntax.
• 404 Not Found: Resource doesn’t exist.
• 500 Internal Server Error: Server-side issue.

For example, a 404 should be returned for a nonexistent endpoint. Discuss how status codes improve user experience and streamline error handling.

How Do You Ensure REST API Security?

API security is critical, and this question tests your ability to safeguard data and prevent attacks. Interviewers want practical, real-world solutions.

• Authentication: Use OAuth 2.0 or JWT to verify users.
• Authorization: Implement role-based access to restrict resources.
• Encryption: Use HTTPS to protect data in transit.
• Rate Limiting: Cap requests to prevent abuse.

Real-world insight: A startup I collaborated with cut API misuse by 75% with rate limiting and JWT authentication. Sharing such examples adds credibility.

What is the Difference Between REST and SOAP?

This question evaluates your knowledge of API protocols. REST and SOAP both enable web services but differ in approach.

• REST: Lightweight, uses JSON, stateless, ideal for web apps.
• SOAP: Protocol-based, uses XML, stateful, suits enterprise systems with strict security.
• Use Case: REST powers mobile apps; SOAP fits complex, secure systems.

Be ready to discuss trade-offs, like REST’s ease versus SOAP’s robust standards.

Tips to Ace REST API Interview Questions

To nail REST API questions, preparation and communication are key. Here’s how to stand out:

• Practice Hands-On: Build a REST API with Express.js or Flask to grasp endpoints.
• Use Coensio: Practice API questions on Coensio’s AI-powered platform for feedback.
• Explain Clearly: Break down answers as if teaching a friend.
• Study Real APIs: Check out GitHub’s or Twitter’s APIs to see REST in action.

Myth buster: You don’t need to memorize every status code—just know the main ones and their categories (e.g., 2xx for success, 4xx for client errors).

Conclusion: Master REST API Interviews with Confidence

REST API interview questions are your chance to show off your technical chops. By mastering HTTP methods, status codes, security practices, and the REST vs. SOAP debate, you’ll be ready to impress. Practice explaining your thought process clearly, and weave in real-world examples to stand out. With these tips, you’re well on your way to acing your next developer interview.