Preparing for rest api interview questions can be the tipping point between an average and an outstanding interview performance. Recruiters in every industry—from fintech to e-commerce—use these queries to separate candidates who merely “know the jargon” from those who can design, secure, and scale real-world services. By mastering the 30 essentials below, you’ll walk into your next discussion with clarity, confidence, and the ability to showcase tangible impact.
“Success is where preparation and opportunity meet.” — Bobby Unser
Verve AI’s Interview Copilot is your smartest prep partner—offering mock sessions on rest api interview questions, role-specific drills, and feedback in real time. Start for free at https://vervecopilot.com.
What Are Rest Api Interview Questions?
Rest api interview questions focus on the concepts, patterns, and best practices that govern Representational State Transfer architecture. They explore everything from HTTP verbs and URI design to caching, concurrency, and security. Candidates can expect scenario-based prompts as well as definition-driven ones that reveal depth of understanding, design thinking, and practical troubleshooting skills.
Why Do Interviewers Ask Rest Api Interview Questions?
Technical mastery—does the candidate understand the stateless, resource-oriented paradigm?
Applied problem solving—can they translate business needs into reliable endpoints?
Engineering maturity—have they considered scalability, security, and maintainability?
Hiring managers lean on rest api interview questions to evaluate three core dimensions:
Your answers help interviewers predict on-call performance, cross-team communication, and long-term contribution.
Preview List: The 30 Rest Api Interview Questions
What is REST, and what does it stand for?
What is a REST API?
What are the key characteristics of a RESTful system?
What are HTTP methods commonly used in REST APIs?
What is the purpose of a URI in REST APIs?
How do you handle errors in REST APIs?
What is HATEOAS in REST APIs?
What is idempotency in REST APIs?
How do you handle pagination in REST APIs?
What are cache-control headers used for?
How do you implement rate limiting in REST APIs?
What is a payload in REST APIs?
What are some common security practices for REST APIs?
How do you test REST APIs?
What is the difference between PUT and PATCH in REST APIs?
What are the benefits of using REST APIs?
How do you document REST APIs?
What is the role of a request body in REST APIs?
What is the purpose of HTTP headers in REST APIs?
How do you handle CORS in REST APIs?
What are RESTful web services?
What are features of RESTful web services?
Explain ‘Addressing’ in RESTful web services.
How do you optimize performance in REST APIs?
What are some common mistakes in designing REST APIs?
How do you version REST APIs?
What is the role of API gateways in REST APIs?
How do you handle concurrent updates in REST APIs?
What are some common testing frameworks for REST APIs?
How do you measure the success of a REST API?
Below you’ll find each question with guidance on motivation, strategy, and an example response.
1. What is REST, and what does it stand for?
Why you might get asked this: Interviewers often open with this foundational prompt to gauge whether you can clearly articulate the underlying architectural style before diving into deeper rest api interview questions. A concise, accurate definition signals that you grasp the resource-oriented nature of REST, its stateless constraints, and why these principles lead to scalable, loosely coupled systems.
How to answer: Start by expanding the acronym Representational State Transfer, then list its six constraints—client-server, statelessness, cacheability, uniform interface, layered system, and optional code-on-demand. Connect each to practical benefits like horizontal scaling or independent evolution of client and server. Conclude by noting that REST is an architecture, not a protocol.
Example answer: “REST stands for Representational State Transfer. It’s an architectural style that treats everything as a resource identified by a URI. Because the client and server are separate, each request is stateless, meaning all required context travels with the call. Caching rules can be layered in to reduce load, and a uniform interface keeps interactions predictable. In my previous project, these principles let us redesign a legacy SOAP service into lightweight REST endpoints, cutting average response time by 45 percent.”
2. What is a REST API?
Why you might get asked this: Clarifying the relationship between REST and API helps interviewers confirm you can translate abstract concepts into practical interfaces. It also sets a baseline for more advanced rest api interview questions about design patterns and error handling.
How to answer: Define an API as a contract that allows applications to communicate, then explain how a REST API adheres to REST constraints using HTTP as its application layer. Mention resource representation formats such as JSON or XML and touch on CRUD mappings.
Example answer: “A REST API is an application programming interface that implements REST principles over HTTP. Each resource—users, orders, or invoices—is addressable via a unique URI, and standard verbs like GET, POST, PUT, or DELETE map to common CRUD operations. Data travels as representations, most often JSON, so the client can remain platform-agnostic. When we exposed our inventory service as a REST API, mobile and web teams consumed the same endpoints, accelerating feature delivery.”
3. What are the key characteristics of a RESTful system?
Why you might get asked this: Understanding the defining traits—rather than parroting a definition—demonstrates real fluency. Interviewers use this to assess your ability to design, review, or refactor services in line with industry-accepted rest api interview questions guidelines.
How to answer: Enumerate the core constraints, add a brief benefit for each, and illustrate how they interact. For instance, statelessness enables horizontal scaling, while cacheability reduces server churn.
Example answer: “A truly RESTful system follows six constraints. Client-server separation allows independent evolution of UI and backend. Statelessness keeps requests self-contained, which is why we can spin up extra pod replicas under Kubernetes so easily. Cacheability labels responses so proxies can serve repeat requests. A uniform interface—resources, URIs, standard verbs—means new team members ramp faster. Layered systems add intermediaries like gateways without breaking the contract. Finally, code-on-demand is optional but lets us, for example, serve JavaScript fragments dynamically.”
4. What are HTTP methods commonly used in REST APIs?
Why you might get asked this: The mapping of business actions to HTTP verbs is a staple among rest api interview questions. Interviewers want to know if you use the protocol idiomatically instead of forcing everything into POST.
How to answer: List the main methods—GET, POST, PUT, PATCH, DELETE, OPTIONS, and HEAD—then link them to safe or idempotent characteristics. Mention when to prefer PUT versus PATCH.
Example answer: “GET fetches data and is both safe and idempotent. POST creates new resources and may trigger side effects. PUT fully replaces a resource and is idempotent; PATCH partially updates. DELETE removes a resource and is idempotent too. OPTIONS is for CORS pre-flight, and HEAD returns headers only. In our order-processing microservice, using PUT for an address update let us retry safely if the network wobbled because the end state never changed.”
5. What is the purpose of a URI in REST APIs?
Why you might get asked this: Clean, intuitive URIs are hallmarks of good API design. This question checks whether you treat URIs as stable resource identifiers or just random endpoints.
How to answer: Explain that a URI uniquely identifies a resource, enabling discoverability and cache keys. Touch on best practices such as nouns over verbs and hierarchical structure.
Example answer: “A URI is the address of a resource, similar to a file path on a disk. Good URIs use nouns—/customers/42 rather than /getCustomer—and nest logically, so /customers/42/orders/7 reads naturally. Well-designed URIs also become cache keys, letting CDNs serve static data instantly. When we revamped our public API, we standardized URIs and saw support tickets drop by 30 percent because developers could guess endpoints more reliably.”
6. How do you handle errors in REST APIs?
Why you might get asked this: Robust error handling distinguishes production-ready services from prototypes. Interviewers use rest api interview questions on errors to probe your empathy for client developers and your alignment with HTTP semantics.
How to answer: Discuss using standard status codes (400, 404, 409, 500), structured response bodies containing an error code, message, and correlation ID, plus logging and observability.
Example answer: “I map application exceptions to the closest HTTP status: validation failures to 422, not-found to 404, and unhandled fallbacks to 500. The JSON body carries an internal code, human-friendly message, and a trace ID so clients can cite it. Our API gateway logs that ID too, so support can correlate the call in seconds. This approach cut mean time to resolution during outages by almost half.”
7. What is HATEOAS in REST APIs?
Why you might get asked this: Hypermedia is often a stumbling block. By inserting it among rest api interview questions, interviewers see whether you appreciate discoverability and self-documentation.
How to answer: Define Hypermedia As The Engine Of Application State, explain link relations, and mention maturity models like Richardson levels.
Example answer: “HATEOAS means the server includes hyperlinks in responses, guiding the client to allowable next actions. For example, a GET on /orders/7 might embed links to /orders/7/cancel or /orders/7/pay. This decouples clients from hard-coded URI paths and aligns with Richardson Level 3. In practice, our mobile app read these links to decide which buttons to render, reducing version-lock headaches.”
8. What is idempotency in REST APIs?
Why you might get asked this: Payment gateways, retry logic, and distributed systems rely on idempotent calls. Hence it’s a fixture in rest api interview questions.
How to answer: Describe the property—same effect no matter how many times it’s executed—connect to safety and retries, cite which HTTP verbs are idempotent by spec.
Example answer: “If I send a DELETE /users/99 ten times, the user is still gone once—that’s idempotency. GET, PUT, DELETE, and HEAD are idempotent; POST is not. For payment capture, we introduced an Idempotency-Key header so clients could safely retry without double-charging. Monitoring confirmed zero duplicate transactions after rollout.”
9. How do you handle pagination in REST APIs?
Why you might get asked this: Large datasets can cripple performance. Rest api interview questions on pagination reveal if you design for scalability and UX.
How to answer: Compare offset-limit, page-size, and cursor strategies. Talk about metadata fields—total, next, previous—and HATEOAS links.
Example answer: “We usually expose limit and offset, e.g., /products?limit=50&offset=150, and return totalCount plus next and prev links. For high-volume timelines, we switch to cursor-based pagination with a createdAt token to avoid expensive counts. Adoption of cursor pagination slashed DB CPU by 35 percent during peak browsing.”
10. What are cache-control headers used for?
Why you might get asked this: Proper caching is low-hanging performance fruit. Interviewers slip this into rest api interview questions to test your familiarity with HTTP spec.
How to answer: Discuss directives like public, private, max-age, no-store, and how they influence browser or CDN behaviour.
Example answer: “Cache-Control governs how intermediaries store a response. A static catalog call might be public, max-age=3600, letting CloudFront serve thousands of requests without touching origin. Sensitive user data is private, no-store. We toggled these headers based on resource type and shaved average latency by 70 milliseconds.”
11. How do you implement rate limiting in REST APIs?
Why you might get asked this: Protection against abuse and cost overruns is critical. Rest api interview questions on rate limiting show whether you understand operational safeguards.
How to answer: Outline algorithms—fixed window, sliding log, token bucket—plus advantages of API gateways, Redis counters, or cloud-native throttling.
Example answer: “Our gateway applies a token-bucket limit: 1,000 tokens refill per minute per API key. When tokens run out, it returns 429 Too Many Requests with a Retry-After header. Limits scale via Redis, and dashboards alert if usage spikes abnormally. This shielded us from a scraping bot that would have cost an extra $4,000 in one weekend.”
12. What is a payload in REST APIs?
Why you might get asked this: A basic yet vital term, it checks shared vocabulary before deeper rest api interview questions about body validation or size optimization.
How to answer: Define payload as the body content sent or received, mention formats and validation.
Example answer: “The payload is the meat of the HTTP message—JSON, XML, or multipart data—inside the body. For POST /signup, the payload could be name and email. We validate payloads against JSON Schema to reject malformed input at the edge, improving mean processing time by catching errors early.”
13. What are some common security practices for REST APIs?
Why you might get asked this: Security is non-negotiable. This rest api interview questions topic showcases your readiness to operate in production.
How to answer: Mention HTTPS, OAuth 2.0, input sanitization, rate limiting, audit logging, and least-privilege IAM roles.
Example answer: “First, everything sits behind HTTPS with HSTS enabled. We use OAuth 2.0 bearer tokens, rotating keys via AWS Secrets Manager. Payloads pass through a WAF that blocks SQL injection patterns. Fine-grained IAM roles keep microservices locked to the least privilege they need. Since these controls launched, we’ve passed two external pen-tests without critical findings.”
14. How do you test REST APIs?
Why you might get asked this: Quality and confidence hinge on testing depth. Rest api interview questions around testing reveal process discipline.
How to answer: Cover unit tests, contract tests with tools like Postman or Pact, integration suites, and load testing.
Example answer: “I start with unit tests mocking the service layer, then wire in contract tests that spin up the full stack in Docker Compose and assert against OpenAPI definitions. QA runs Postman regression collections nightly, and k6 drives load tests to check 95th percentile latency. This layered approach caught a breaking change in our PATCH endpoint before it hit staging.”
15. What is the difference between PUT and PATCH in REST APIs?
Why you might get asked this: Subtle verb differences often trip candidates. It’s a classic rest api interview questions probe into semantic precision.
How to answer: Explain that PUT replaces the entire resource at the URI, while PATCH partially updates. Mention idempotency and payload composition.
Example answer: “PUT is like overwriting a file; you send the full state. If a customer has fields A, B, C, the payload must contain all three—even unchanged values. PATCH sends only the diff, like {‘email’:‘new@mail.com’}. PUT remains idempotent; PATCH may not, depending on implementation. We chose PATCH for profile edits to cut mobile data usage by 80 percent.”
16. What are the benefits of using REST APIs?
Why you might get asked this: ROI matters to business stakeholders. Interviewers want to see if you can evangelize APIs beyond code—another angle in rest api interview questions.
How to answer: List scalability, loose coupling, cacheability, language independence, and alignment with web standards.
Example answer: “REST leverages ubiquitous HTTP, so browsers, Postman, or cURL all work out of the box. Statelessness makes horizontal scaling dead simple; we autoscale pods on CPU without sticky sessions. Caching slashes latency, and the text-based protocol keeps debugging easy. These benefits let our team deliver faster while Ops keeps costs predictable.”
17. How do you document REST APIs?
Why you might get asked this: Usability equals adoption. This rest api interview questions angle gauges empathy for other developers.
How to answer: Discuss OpenAPI/Swagger, interactive consoles, examples, and change logs.
Example answer: “We describe every endpoint in an OpenAPI 3 spec, auto-generate Swagger UI, and embed examples for 200 and 4xx responses. A docs-as-code workflow gates pull requests; if spec tests fail, the merge blocks. After launching the self-service portal, external integrators cut onboarding time from two weeks to three days.”
18. What is the role of a request body in REST APIs?
Why you might get asked this: Clears up confusion over query parameters versus body—common in rest api interview questions.
How to answer: Explain that the body carries data to create or update a resource, while GET requests typically omit bodies.
Example answer: “Whenever the client needs to send substantial data—sign-up details, an image, or a JSON patch—it goes into the request body. For a POST /orders, the body lists item IDs and quantities. The server validates it against schema before persisting. Using the body keeps URIs clean and avoids length limits.”
19. What is the purpose of HTTP headers in REST APIs?
Why you might get asked this: Headers are small yet mighty. Rest api interview questions on headers test low-level HTTP knowledge.
How to answer: Cover metadata such as Content-Type, Authorization, Accept, and custom correlation IDs.
Example answer: “Headers describe the message: Content-Type tells the server it’s application/json, Accept says what formats the client can parse, Authorization carries the bearer token, and X-Request-ID tracks the call across microservices. Proper header usage improved our distributed tracing across eight services.”
20. How do you handle CORS in REST APIs?
Why you might get asked this: Frontend integration often stumbles here. It’s a practical rest api interview questions favorite.
How to answer: Explain the same-origin policy, pre-flight OPTIONS request, and Access-Control-Allow-Origin plus credentials.
Example answer: “Browsers block cross-origin calls unless the server whitelists them. Our API gateway responds to OPTIONS with Access-Control-Allow-Origin: https://app.acme.com and lists allowed methods. We avoid wildcard origins in production and rotate allowed domains via config, cutting false-positive security scanner alerts.”
21. What are RESTful web services?
Why you might get asked this: This term often appears in job specs. Rest api interview questions here ensure shared understanding.
How to answer: Define RESTful web services as network services adhering to REST architecture, accessible over HTTP, returning resource representations.
Example answer: “A RESTful web service is basically an HTTP-based API that follows REST constraints. Instead of an RPC-style call like getUser, you GET /users/7 and receive JSON. The same service might live behind an API gateway, scale via containers, and be discoverable through service registry.”
22. What are features of RESTful web services?
Why you might get asked this: Drills deeper into the previous query, revealing your ability to discuss quality attributes in rest api interview questions.
How to answer: Mention platform independence, layered architecture, easy caching, uniform interface, and lightweight nature.
Example answer: “They’re platform-agnostic—anything that speaks HTTP can consume them. Statelessness makes them easy to distribute across regions. Because they leverage standard verbs and media types, documentation is simpler. All these features let our small team serve 50 million requests per day without rewriting the client apps.”
23. Explain ‘Addressing’ in RESTful web services.
Why you might get asked this: Proper addressing underpins discoverability. It’s a niche yet insightful rest api interview questions angle.
How to answer: Describe how URIs uniquely identify resources, enabling bookmarkable links, caching, and hyperlinks.
Example answer: “Addressing is about giving every resource a clear, dereferenceable URI. Think of it like street addresses: /customers/123. Consistent addressing lets clients manipulate resources with standard verbs and enables search engines or caching proxies to understand the hierarchy.”
24. How do you optimize performance in REST APIs?
Why you might get asked this: Speed equals user satisfaction and lower costs. Rest api interview questions on optimization test breadth.
How to answer: Cover caching, query optimization, pagination, compression (gzip), connection pooling, and CDN usage.
Example answer: “First, we set appropriate Cache-Control headers. Second, we profile DB queries and add indexes or use read replicas. Third, payloads are gzipped, and we strip unnecessary fields via sparse fieldsets. A CloudFront layer serves static GETs. These steps cut our P95 latency from 650 ms to 180 ms.”
25. What are some common mistakes in designing REST APIs?
Why you might get asked this: Learning from pitfalls shows maturity—hence its place among rest api interview questions.
How to answer: Mention verbs in URIs, inconsistent naming, ignoring versioning, overloading POST, poor error codes, and leaking internal stack traces.
Example answer: “I’ve seen /createUser or /updateAddress endpoints that violate REST by embedding verbs. Another pitfall is mixing snake_case and camelCase. Skipping versioning makes backwards compatibility tough. Finally, returning 200 OK with an error message in the body drives client teams crazy.”
26. How do you version REST APIs?
Why you might get asked this: Stability for consumers is key. This rest api interview questions topic checks forward-thinking.
How to answer: Compare URI versioning (/v1/), header versioning, and query parameters, discussing pros and cons.
Example answer: “We prefer URI versioning—/v2/orders—because it’s explicit and cache-friendly. For breaking changes like switching currency precision, we stand up the new version and sunset v1 over six months. Headers work too but are less discoverable in browsers. With clear deprecation notices, we migrated 95 percent of clients without incident.”
27. What is the role of API gateways in REST APIs?
Why you might get asked this: Gateways consolidate cross-cutting concerns. Rest api interview questions on this reveal architectural savvy.
How to answer: Explain routing, authentication, rate limiting, aggregation, and monitoring.
Example answer: “Our gateway is the front door handling TLS termination, OAuth token validation, and per-client throttling. It routes /billing/ to one cluster and /search/ to another. Centralized logging means we capture metrics like error rate in a single Grafana dashboard. This abstraction lets backend teams focus on business logic.”
28. How do you handle concurrent updates in REST APIs?
Why you might get asked this: Data integrity in distributed systems is a complex domain. Inclusion in rest api interview questions separates entry-level from advanced candidates.
How to answer: Describe optimistic locking with ETags or If-Match headers, and pessimistic approaches like DB row locks.
Example answer: “We return an ETag header representing the record version. Clients send If-Match with that tag when updating. If another change occurred, the server responds 412 Precondition Failed. This optimistic strategy avoids deadlocks and kept our support ticket count for ‘lost updates’ cases at virtually zero.”
29. What are some common testing frameworks for REST APIs?
Why you might get asked this: Tool familiarity equals productivity—thus it rounds out many rest api interview questions.
How to answer: Name Postman, REST Assured, JUnit, PyTest, Newman, and CI integration.
Example answer: “For Java we lean on REST Assured inside JUnit suites, while QA runs Postman collections via Newman in the CI pipeline. Python microservices rely on PyTest with HTTPX. Automated tests catch schema drift before merge, keeping our master branch always releasable.”
30. How do you measure the success of a REST API?
Why you might get asked this: Business impact matters. This final rest api interview questions prompt shows strategic thinking.
How to answer: Discuss KPIs: adoption rate, error rate, latency, NPS from developers, and business metrics enabled.
Example answer: “We track call volume growth, average latency, and 4xx/5xx ratios in Datadog. A developer NPS survey goes out quarterly. Revenue attributed to partner integrations rose 60 percent after we launched the API, so usage stats and business outcomes together paint a full picture.”
Other Tips To Prepare For A Rest Api Interview Questions
• Rehearse aloud with peers or, better, simulate a real session. Verve AI Interview Copilot lets you practice with an AI recruiter 24/7, leveraging a massive company-specific question bank and giving instant coaching. No credit card needed: https://vervecopilot.com.
• Build a mini-project—nothing teaches faster than implementation.
• Summarize each of these rest api interview questions on flashcards for rapid recall.
• Record yourself answering; evaluate clarity and filler words.
“You don’t have to be great to start, but you have to start to be great.” — Zig Ziglar
Thousands already use Verve AI to nail rest api interview questions. Practice smarter, not harder: https://vervecopilot.com.
Frequently Asked Questions
Q1: Are REST and HTTP the same thing?
No. HTTP is a protocol, while REST is an architectural style that commonly leverages HTTP but can be applied over other protocols.
Q2: Is GraphQL replacing REST?
GraphQL solves different problems—flexible querying and avoiding over/under-fetching. Many teams run both, choosing per use case.
Q3: How important is HATEOAS in modern APIs?
While not always implemented, HATEOAS enhances discoverability and self-documentation, aligning with the highest maturity level of REST.
Q4: Do all REST APIs need versioning?
Yes, if you plan to evolve the API without breaking existing clients. Even seemingly small changes can be breaking.
Q5: What’s the quickest way to get hands-on practice?
Spin up a simple CRUD service with a lightweight framework and test it against these rest api interview questions using Verve AI’s Interview Copilot.
