All 47 questions

  1. What is a REST API?

    Asked in 16 of 377 interviews · last asked Oct 5 · Concept · Junior

    Show answer

    A REST API is an interface that follows REST design rules. It exposes resources, such as users or orders, through URLs and uses HTTP methods to work with them. Each request contains the information needed to handle it, without relying on stored client session state.

    • Use resource URLs, such as /users/42, with methods like GET, POST, PUT, and DELETE.
    • Requests are stateless; the server can still store resource data.
    • Use HTTP status codes to show results, such as 200, 201, or 404.
    • JSON is common, but REST does not require it.
    Code
    GET /users/42

200 OK
Content-Type: application/json

{"id":42,"name":"Sam"}

    What the interviewer checks: The interviewer checks whether you understand resources, HTTP methods, and stateless requests.

    Common mistake (in 5 of 8 reviewed answers): Many answers forget that REST APIs expose resources through URLs and use HTTP methods to work with them.

    Other ways it was asked
    • “What are REST APIs?”
    • “What do you mean by a RESTful API?”
    • “What is the REST API?”

  2. How is GraphQL different from REST?

    Asked in 7 of 377 interviews · last asked Oct 22 · Concept · Mid-level

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    GraphQL is a query language for APIs, while REST is an architectural style. GraphQL lets clients request specific fields and related data, usually through one endpoint. REST APIs usually expose resources through separate URLs and use HTTP methods such as GET and POST. GraphQL can reduce unwanted data and extra requests, but adds query processing complexity.

    • GraphQL defines a typed schema that clients can query.
    • REST APIs can also support field selection and related data; these features are not unique to GraphQL.
    • REST GET responses fit standard HTTP caching more naturally; GraphQL caching often needs extra tooling.
    • GraphQL servers need controls to limit expensive or deeply nested queries.

    What the interviewer checks: The interviewer is checking whether you understand client-driven queries, resource-based APIs, and their trade-offs.

    Other ways it was asked
    • “What are the differences between GraphQL and REST?”
    • “What problem does GraphQL solve compared with REST APIs?”
    • “What is the difference between GraphQL and REST?”

  3. What is the difference between SOAP and REST?

    Asked in 5 of 377 interviews · last asked Oct 15 · Concept · Junior

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    SOAP is a messaging protocol, while REST is an architectural style. SOAP uses XML messages; REST APIs can use JSON, XML, or other formats. REST is often a good fit for web and mobile APIs. Choose SOAP when you need an existing SOAP contract or standards such as WS-Security.

    • SOAP can use HTTP or other transports; REST APIs commonly use HTTP methods and status codes.
    • REST defines constraints such as stateless requests and a uniform interface.
    • SOAP services often use WSDL contracts; REST does not require a specific contract format.
    • Both can be secure; SOAP adds standards for message-level security.

    What the interviewer checks: The interviewer checks whether you distinguish a protocol from an architectural style and explain when each fits.

    Other ways it was asked
    • “What is the difference between REST and SOAP?”
    • “How do SOAP and REST differ, and in what situations would you choose each?”
    • “What is the difference between REST and SOAP API?”

  4. What is an API?

    Asked in 5 of 377 interviews · last asked Sep 30 · Concept · Junior

    Show answer

    An API, or Application Programming Interface, is a set of rules that lets software systems communicate. It defines what one system can request from another and how the result is returned. APIs let developers use features or data without knowing how the other system works inside.

    • An API defines how software can interact.
    • It helps systems share data and reuse features.
    • APIs are not limited to the web; REST APIs are one kind.

    What the interviewer checks: The interviewer wants to know whether you understand what an API does and why software uses it.

    Other ways it was asked
    • “What is an API, and why is it important?”
    • “Can you explain what an API is?”

  5. What is JSON?

    Asked in 3 of 377 interviews · last asked Aug 27 · Concept · Junior

    Show answer

    JSON stands for JavaScript Object Notation. It is a text format used to exchange data, often between a REST API and a client. It supports objects, arrays, strings, numbers, booleans, and null. Despite its name, it works with many programming languages.

    • Objects contain key-value pairs; arrays contain ordered values.
    • Object keys and strings must use double quotes.
    • Standard JSON does not allow comments or trailing commas.
    Code
    {
  "id": 42,
  "name": "Sam",
  "active": true,
  "roles": ["reader"]
}

    What the interviewer checks: The interviewer checks whether you understand JSON’s purpose, basic structure, and syntax.

    Other ways it was asked
    • “Can you tell me about JSON?”

  6. What is the difference between REST APIs and GraphQL, how is GraphQL implemented under the hood, and when should each be used?

    Asked in 2 of 377 interviews · last asked Oct 23 · Concept · Senior

    Other ways it was asked
    • “When would you use a REST API versus GraphQL, and how do they differ?”

  7. How does gRPC work?

    Asked in 2 of 377 interviews · last asked Oct 5 · Concept · Mid-level

    Other ways it was asked
    • “What is gRPC?”

  8. How can a REST API be stateless if a request to retrieve a resource depends on an earlier request that created it?

    Asked once · last asked Jan 29 · Concept · Mid-level

    Other ways it was asked
    • “In a REST API, is creating a resource in one request and retrieving it in a later request considered stateful or stateless?”

  9. What is the difference between stateless and stateful systems in client-server interactions and API calls?

    Asked once · last asked Jan 29 · Concept · Mid-level

  10. Can you create a record in a REST API with one request and retrieve that same record with a subsequent request?

    Asked once · last asked Jan 29 · Concept · Mid-level

  11. How does a component's internal state differ from a resource created through an API?

    Asked once · last asked Jan 29 · Concept · Mid-level

    Other ways it was asked
    • “What is a component's internal state, and does it depend on previous API requests?”

  12. When exposing a service for external consumers, how would you choose between providing API endpoints and publishing a NuGet package?

    Asked once · last asked Apr 2 · Design · Mid-level

  13. What is a REST API, and what are the basic HTTP methods it supports?

    Asked once · last asked Apr 23 · Concept · Junior

  14. What is the difference between developing a REST API and integrating a third-party REST API?

    Asked once · last asked Apr 24 · Concept · Mid-level

  15. What are gRPC and GraphQL used for, and how do they differ from REST?

    Asked once · last asked May 25 · Concept · Mid-level

  16. Can you name some TM Forum APIs and explain their current names and purposes?

    Asked once · last asked Jun 18 · Concept · Senior

    Other ways it was asked
    • “What TM Forum APIs do you work with? Can you name any and say what they are called now?”

  17. What is a REST API, and what other API architectural styles are there?

    Asked once · last asked Jul 16 · Concept · Mid-level

  18. What is the difference between server-side and client-side API calls?

    Asked once · last asked Jul 28 · Concept · Mid-level

    Other ways it was asked
    • “Which is more efficient, client-side or server-side API calls?”

  19. How does calling an API differ from interacting with an MCP server?

    Asked once · last asked Aug 4 · Concept · Mid-level

  20. What are the core architectural differences between REST APIs using JSON and gRPC services?

    Asked once · last asked Aug 5 · Concept · Mid-level

  21. Why would you use WebSockets instead of a REST API?

    Asked once · last asked Sep 13 · Concept · Mid-level

  22. How would you choose between a REST API and SignalR for a chat application, and why?

    Asked once · last asked Sep 18 · Design · Mid-level

  23. If you had to choose between REST and GraphQL for a project, what steps and considerations would guide your decision?

    Asked once · last asked Sep 21 · Scenario · Senior

  24. When working with GraphQL, how does consuming an existing API differ from designing its schema and APIs?

    Asked once · last asked Sep 29 · Concept · Mid-level

  25. When should authentication and file uploads use GraphQL versus separate REST endpoints?

    Asked once · last asked Sep 29 · Scenario · Senior

  26. What is the difference between null and a missing key in JSON?

    Asked once · last asked Oct 11 · Concept · Junior

  27. For a banking system, would you choose SOAP API or REST API?

    Asked once · last asked Oct 12 · Scenario · Mid-level

  28. What is the difference between an API and a tool in the context of an AI agent?

    Asked once · last asked Oct 19 · Concept · Mid-level

  29. Can you explain what a RESTful API is in your own words?

    Asked once · last asked Sep 30 · Concept · Junior

  30. What is the difference between building RESTful APIs in Laravel and integrating with third-party APIs?

    Asked once · last asked May 5 · Concept · Mid-level

  31. What is an API, why is it important for building scalable web applications, and what is a simple example of how you might use one?

    Asked once · last asked May 8 · Concept · Junior

  32. What does REST stand for?

    Asked once · last asked May 9 · Concept · Junior

  33. What is HATEOAS, and what role does it play in REST APIs?

    Asked once · last asked May 22 · Concept · Mid-level

  34. What is an endpoint?

    Asked once · last asked Jun 4 · Concept · Junior

  35. What types of APIs can an application use to communicate with a backend?

    Asked once · last asked Jun 11 · Concept · Junior

  36. What are APIs, and how do you use them in an application?

    Asked once · last asked Jul 22 · Concept · Junior

  37. Why are APIs needed after learning programming fundamentals such as loops, conditionals, and functions?

    Asked once · last asked Aug 3 · Concept · Junior

  38. What are the basic principles of REST APIs?

    Asked once · last asked Aug 14 · Concept · Junior

  39. Can you explain what a REST API is and how it differs from a traditional web application that serves HTML pages?

    Asked once · last asked Aug 15 · Concept · Junior

  40. Why might a document traceability system use REST APIs?

    Asked once · last asked Sep 14 · Concept · Junior

  41. What is over-fetching in GraphQL?

    Asked once · last asked Sep 22 · Concept · Junior

    Other ways it was asked
    • “How does GraphQL help reduce over-fetching?”

  42. Which API approach is more prone to over-fetching: GraphQL or REST?

    Asked once · last asked Sep 22 · Concept · Junior

  43. Why would you recommend Salesforce REST API with JSON?

    Asked once · last asked Sep 30 · Concept · Mid-level

  44. What does synchronous communication mean in gRPC?

    Asked once · last asked Oct 5 · Concept · Mid-level

  45. What API styles or protocols are commonly used besides REST?

    Asked once · last asked Oct 12 · Concept · Junior

  46. What is SOAP?

    Asked once · last asked Oct 15 · Concept · Junior

  47. Which is more complex to develop and maintain: GraphQL or a REST API?

    Asked once · last asked Oct 23 · Concept · Mid-level

More REST API interview questions

How this list is made

Every question here was asked by a real interviewer in a real job interview that a candidate ran MeetAssist in. After the call, the interviewer's questions are pulled from the transcript. Practice sessions, tests, exams and anything that was not a job interview are dropped.

Questions are rewritten so they make sense on their own: names of people, employers and clients are removed, and speech-to-text mistakes are fixed. Small talk, logistics and questions about one candidate's own résumé are left out. Rephrasings of the same question are merged, and the count is the number of different interviews it came up in.

The interviews come from candidates who use MeetAssist, so they lean towards software, data and AI roles: the shares describe these interviews, not every REST API interview. Answers to the most asked questions are written and checked by an editor; a "common mistake" is shown only when reviews of real answers in these interviews show it, with the count.

377 interviews, 243 candidates, Jan 2026 to Oct 2026. Updated every month with new interviews.