Ace your API testing interview with 40 real-world questions covering REST, Postman, status codes, authentication, contract testing and more. Free, with hands-on examples.
Answer: API (Application Programming Interface) enables communication between different software systems. API testing validates that these interfaces work correctly — checking request/response structures, status codes, data integrity, error handling and performance.
Answer: REST (Representational State Transfer) is an architectural style for designing networked applications. REST APIs use HTTP methods (GET, POST, PUT, PATCH, DELETE) and return data in JSON or XML format.
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If you can confidently answer the API Testing Fundamentals questions above, you're well prepared for this section of your interview. Move on, or rehearse the trickier ones aloud with our AI mock interviewer.
Answer: Postman is a popular API testing tool for sending requests, validating responses and automating API tests. Key features: collections, environments, pre-request scripts, test scripts (JavaScript), and the Collection Runner.
pm.test("Status code is 200", function () {
pm.response.to.have.status(200);
});
pm.test("Response time is less than 500ms", function () {
pm.expect(pm.response.responseTime).to.be.below(500);
});
pm.test("Response contains expected data", function () {
const jsonData = pm.response.json();
pm.expect(jsonData.id).to.eql(123);
});Answer: Use pm.environment.set() in the Tests tab of the first request to store values (like auth tokens) and reference them in subsequent requests.
// Store token from login response
const jsonData = pm.response.json();
pm.environment.set("auth_token", jsonData.token);Learn more on our API Testing interview questions page.
If you can confidently answer the API Testing with Postman questions above, you're well prepared for this section of your interview. Move on, or rehearse the trickier ones aloud with our AI mock interviewer.
If you can confidently answer the Authentication & Authorization questions above, you're well prepared for this section of your interview. Move on, or rehearse the trickier ones aloud with our AI mock interviewer.
Answer: Contract testing verifies that API providers and consumers agree on the interface. Tools: Pact, Spring Cloud Contract. Ensures changes don't break consumers.
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If you can confidently answer the API Testing Scenarios & Techniques questions above, you're well prepared for this section of your interview. Move on, or rehearse the trickier ones aloud with our AI mock interviewer.
If you can confidently answer the REST, SOAP & GraphQL questions above, you're well prepared for this section of your interview. Move on, or rehearse the trickier ones aloud with our AI mock interviewer.
| Tool | Best For |
|---|---|
| Postman | Quick manual + automation |
| REST Assured | Java projects, CI/CD |
| Supertest (Node.js) | JavaScript/TypeScript projects |
| Requests (Python) | Python automation |
| Playwright API Testing | Combined UI + API tests |
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If you can confidently answer the API Automation & CI/CD questions above, you're well prepared for this section of your interview. Move on, or rehearse the trickier ones aloud with our AI mock interviewer.
Answer: Validating that API responses match a predefined JSON schema — checking data types, required fields and structure.
const schema = {
type: "object",
required: ["id", "name", "email"],
properties: {
id: { type: "number" },
name: { type: "string" },
email: { type: "string", format: "email" }
}
};
pm.test("Schema is valid", function() {
pm.response.to.have.jsonSchema(schema);
});If you can confidently answer the Advanced API Testing Concepts questions above, you're well prepared for this section of your interview. Move on, or rehearse the trickier ones aloud with our AI mock interviewer.