Full stack developer interview questions

Full stack developer interview questions and answers

Full stack interviews check that you can build a feature end to end: the UI, the API, the database and getting it deployed. These are the questions that come up most, with what each one checks.

What to revise before the interview

  • HTTP: methods, status codes, headers, cookies
  • REST API design and versioning
  • Authentication: sessions vs JWT, password hashing
  • SQL vs NoSQL and basic schema design
  • Node.js: the event loop, Express middleware
  • React fundamentals and data fetching
  • Caching, pagination and rate limiting
  • Deployment: environment variables, CI/CD basics

  1. 1.What happens when you type a URL into the browser?

    What they're checking
    A broad question that shows how well you understand the whole stack.
    How to answer
    DNS lookup, TCP and TLS connection, HTTP request, server processing (routing, database), response, then the browser parses HTML, loads CSS and JavaScript and renders. Go deeper wherever the interviewer asks.

  2. 2.How do you design a REST API for a simple blog?

    What they're checking
    API design skills.
    How to answer
    Resources as nouns: GET /posts, POST /posts, GET /posts/:id, PATCH /posts/:id, DELETE /posts/:id, and /posts/:id/comments. Mention status codes, validation, pagination and authentication.

  3. 3.Sessions vs JWT - how do they differ?

    What they're checking
    Authentication understanding and security sense.
    How to answer
    Sessions store state on the server and send a session ID cookie; JWTs carry signed claims the server can verify without a lookup. JWTs are harder to revoke, so keep them short-lived. Always hash passwords with bcrypt or similar.

  4. 4.When would you choose SQL over NoSQL?

    What they're checking
    Data modelling judgement.
    How to answer
    SQL for structured, related data and transactions - orders, payments. NoSQL for flexible documents or very high write volumes. Most apps are well served by a relational database.

  5. 5.What is middleware in Express?

    What they're checking
    Node.js backend basics.
    How to answer
    Functions that run in order on each request with (req, res, next) - for logging, parsing JSON, authentication and error handling. The error handler takes four arguments and goes last.

  6. 6.How would you add pagination to an API?

    What they're checking
    Thinking about scale.
    How to answer
    Offset and limit is simple but slow on large tables and shifts when data changes; cursor-based pagination (after the last ID or timestamp) is faster and stable. Return the next cursor in the response.

  7. 7.How do you prevent common security issues?

    What they're checking
    Security awareness across the stack.
    How to answer
    Parameterised queries against SQL injection, escaping output against XSS, CSRF protection for cookie sessions, CORS set to known origins, rate limiting on login, and secrets kept in environment variables.

  8. 8.Where would you add caching, and what are the risks?

    What they're checking
    Performance thinking.
    How to answer
    Browser and CDN caching for static files, an in-memory or Redis cache for expensive reads. The risk is stale data, so decide how and when entries expire or are cleared on writes.

  9. 9.How do you deploy your application?

    What they're checking
    Whether you've shipped anything real.
    How to answer
    Describe your actual setup: where the frontend and API are hosted, how environment variables are managed, how the database is migrated and how a push to the main branch triggers a deploy.

  10. 10.Tell me about a feature you built end to end.

    What they're checking
    Ownership across layers.
    How to answer
    Cover the UI, the API, the database change and one problem you solved. Mention how you tested it.
    Example answer
    “I built a comments feature: a React form with optimistic updates, a POST endpoint with validation and rate limiting, and a comments table with an index on post_id. The hard part was handling a failed save after the comment already showed, which I solved by rolling it back with an error message.”

On a live call, Cuelyte AI hears questions like these and has an answer ready in about a second, built from your resume and notes. Coding interviews: how Cuelyte AI helps

Frequently asked questions

Which stack should I learn for full stack interviews?

Any common stack works - MERN (MongoDB, Express, React, Node), or React with a Java, Python or .NET backend. Depth in one stack and a deployed project matter more than knowing many.

Do full stack interviews include DSA?

Many do, especially at product companies. Expect at least one coding round on arrays, strings and hash maps alongside the web questions.

What projects impress in full stack interviews?

One deployed app with authentication, a database and a real use - and your ability to explain every decision in it.

Company interview guides for this role

Related roles and topics

Practise these questions for your next interview

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