Full stack interviews test breadth: frontend, backend, databases, APIs, and — crucially — how it all connects. You don't need to be the deepest specialist in any one layer, but you must understand how a request travels from browser to database and back. Here are the full stack developer interview questions that actually get asked.
Frontend
- JavaScript core, the DOM, and a framework like React (our React and JavaScript guides).
- HTML/CSS — the box model, flexbox, responsive design (our HTML/CSS guide).
- State management; how the frontend talks to the backend.
Backend & APIs
- Building REST APIs — methods, status codes, auth (our REST guide).
- Authentication — sessions vs JWT.
- Server-side logic and error handling (our backend guide).
Databases & the full picture
- SQL vs NoSQL; basic queries and modeling (our SQL guide).
- How does a request flow from frontend to database and back?
- Caching, and where you'd add it.
- A small system design — design a simple app end to end (our guide).
How to prepare
Full stack rounds probe how the pieces connect, verbally. Practise explaining the request lifecycle and your architecture choices out loud. Greenroom runs spoken technical interviews that follow up on your reasoning. Pair it with our backend and frontend guides.
Frequently asked questions
What questions are asked in a full stack developer interview?
Full stack interviews cover frontend (JavaScript, the DOM, a framework like React, HTML/CSS), backend (REST APIs, authentication with sessions vs JWT, server-side logic), databases (SQL vs NoSQL, queries, modeling), how a request flows end to end, caching, and a small system design. The emphasis is on understanding how all the layers connect.
What does a full stack developer need to know?
A full stack developer needs working knowledge across the stack: a frontend framework and core JavaScript/HTML/CSS, backend development and REST API design, authentication, database fundamentals (SQL and NoSQL), and how the layers communicate. You don't need to be the deepest specialist in each, but you must understand how a request travels from browser to database and back.
How do I explain the request lifecycle in an interview?
Walk through it end to end: the browser sends an HTTP request (often triggered by frontend JavaScript), it hits the backend server which authenticates and runs business logic, the backend queries the database and gets results, the server formats a response (often JSON), and the frontend receives it and updates the UI. Mentioning caching, error handling and status codes shows depth.
How should I prepare for a full stack developer interview?
Build breadth across frontend, backend and databases, but focus on how the layers connect — the request lifecycle, where bugs could live, and end-to-end data flow — since connective understanding is what's tested. Practise explaining the request lifecycle and your architecture choices out loud with a voice-based mock interview that follows up.