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Full Stack Developer interview questions

Full stack interviews go broad: you will be asked about the browser, the API and the database in the same conversation. The strongest signal is a project you built end to end and can explain layer by layer, including how you deployed it.

10 questions with answer notes · 4 rounds · By the JOBSPOT 360 team

How the selection process usually works

  1. 1

    Online assessment

    DSA problems and MCQs covering JavaScript, SQL and HTTP.

  2. 2

    Frontend round

    JavaScript fundamentals and a small UI task in React, Angular or Vue.

  3. 3

    Backend and database round

    API design, SQL queries, authentication and schema design.

  4. 4

    Project deep-dive and HR

    Architecture of your best project, deployment, then HR discussion.

Rounds vary between companies. Smaller teams often merge the technical and managerial rounds, while larger companies may add an extra technical round.

Skills to brush up on

  • JavaScript and TypeScript
  • React, Angular or Vue
  • Node.js, Laravel, Django or Spring Boot
  • SQL (MySQL or PostgreSQL) and MongoDB basics
  • REST API design
  • Authentication (sessions, JWT, OAuth)
  • Git
  • Docker and basic cloud deployment

Technical questions

  1. 01 Explain the full request flow when a user submits a login form in your app.

    How to answer: Form validation in the browser, the HTTPS request, server-side validation, password hash check, session or token creation, the response, and how the frontend stores the auth state.

  2. 02 What is CORS and how do you fix a CORS error?

    How to answer: A browser rule that blocks cross-origin requests unless the server allows them. Fix it on the server with the correct Access-Control-Allow-* headers, not in the frontend.

  3. 03 SQL or NoSQL: how do you choose?

    How to answer: Use SQL for relational data that needs joins and transactions; document stores suit flexible, nested data with simple access patterns. Most apps are fine with SQL.

  4. 04 Where should validation happen, on the client or the server?

    How to answer: Both. Client-side validation is for user experience; server-side validation is for security and must never be skipped.

  5. 05 What is server-side rendering and when is it worth it?

    How to answer: HTML is rendered on the server for faster first paint and better SEO. It is worth it for public, content-heavy pages; dashboards behind a login often do not need it.

  6. 06 How do you handle file uploads securely?

    How to answer: Validate type and size on the server, store files outside the web root or in object storage with generated names, and serve them through signed URLs if they are private.

  7. 07 How do you manage environment-specific configuration and secrets?

    How to answer: Use environment variables, keep .env files out of Git, and use a secrets manager in production.

Scenario questions

  1. 01 Build a to-do app with an API and a UI in 90 minutes. What do you build first?

    How to answer: Agree on the data model and API contract, build the thinnest working slice end to end, then add validation, error states and polish.

  2. 02 Users report the dashboard is slow. How do you find out if it is the frontend or the backend?

    How to answer: Check the network tab: slow API responses point to the backend; fast responses with slow rendering point to the frontend. Then profile that side.

  3. 03 How would you deploy your project so it survives a server restart?

    How to answer: Use a process manager or containers, a managed database, environment-based config, and a CI pipeline that runs tests before deploying.
Then comes the HR round Almost every interview ends with HR questions about you, your plans and your salary expectations. See the common ones and how to answer them.

Resume tips for this role

  • Feature one end-to-end project with a live link, the stack for each layer and how it is deployed.
  • Split skills into Frontend, Backend, Database and DevOps so recruiters can scan them quickly.
  • Show ownership: "built and deployed" is stronger than "worked on".
  • Keep tutorial clones off the resume unless you extended them significantly.

This guide is written by the JOBSPOT 360 team from common interview patterns for this kind of role. It is not provided by any employer, and real interviews will differ. Read our editorial policy.