Oct 08, 2026 by Offer

What is an API (How To Answer): Interview Answer Guide 2027

An API — Application Programming Interface — is a contract letting software components communicate without knowing each other's internals. A good api interview question answer explains REST concretely: resources at URLs, HTTP verbs (GET, POST, PUT, DELETE) as actions, status codes as results, and JSON as the message format — with one example request.

What the Api Interview Question Tests

Whether you can define an API without jargon: a contract between software, hiding implementation.
Whether you know REST mechanics: verbs, status codes, JSON payloads, statelessness.
Whether you can walk through a real example, e.g., GET /users/123 returning 200 with JSON.

How to Answer the API Interview Question

Deliver it as definition, mechanics, then a live trace:

One-line definition. "An API is a contract for software-to-software interaction that hides implementation."
REST mechanics. URLs name resources; GET/POST/PUT/DELETE act on them; status codes report results.
Trace one call. "GET /orders/42 → server looks up order 42 → responds 200 with JSON, or 404 if it doesn't exist."
Show design sense. "Good APIs are stateless, versioned, and use precise status codes so clients can react correctly."

Sample 30-second answer: "An API lets programs talk through a defined contract. In REST, GET /users/123 asks for user 123; the server returns 200 with JSON or 404 if missing. Verbs say what to do, status codes say what happened, and the client never sees the internals."

Common Mistakes With the Api Interview Question

Defining API as 'a way to get data' only — APIs also trigger actions and hide implementation, not just serve data.
Mixing up PUT and PATCH, or using GET for state-changing operations.
Ignoring status codes: returning 200 for everything hides errors from clients.

'What is an API' filters for communication skills as much as knowledge: everyone uses APIs, but strong candidates explain the contract idea and walk a request lifecycle crisply. Have your one example rehearsed.

Keep Reading

FAQ

What is an API in simple terms?

A defined way for software to request services from other software — like a menu: you order by name without knowing how the kitchen works.

What is a REST API?

An API style using HTTP: resources have URLs, verbs (GET/POST/PUT/DELETE) say what to do, and responses carry status codes plus data, usually JSON.

What is the difference between PUT and POST?

POST typically creates a new resource; PUT replaces a resource at a known URL idempotently — repeating it has the same effect.

What are common HTTP status codes?

200 OK, 201 Created, 400 Bad Request, 401 Unauthorized, 404 Not Found, 500 Internal Server Error. Codes tell the client what happened without reading the body.

Preparing for TikTok's interview? Our 2027 TikTok Online Hackerrank Coding Assessment Tutorials has practice questions and answers — $79 one-time, instant download.