Top 100 full-stack developer interview questions and answers

Here’s a comprehensive list of top 100 full-stack developer interview questions and answers covering front-end, back-end, database, and general topics. Due to the character limit, I’ll list key questions and answers in various categories. Let me know if you’d like this expanded or need a document for easier reference.

General Full-Stack Questions

1. What is a Full-Stack Developer? A full-stack developer works on both front-end (client-side) and back-end (server-side) parts of a web application.
2. What is the difference between full-stack and MEAN/MERN stack?MEAN: MongoDB, Express.js, Angular, Node.jsMERN: MongoDB, Express.js, React, Node.js These are JavaScript-based stacks, while “full-stack” is a general term for working on both front-end and back-end.
3. What is RESTful API? REST (Representational State Transfer) is an architectural style for designing networked applications using stateless communication via HTTP.
4. What is the difference between SQL and NoSQL databases?SQL: Relational, structured schema (e.g., MySQL, PostgreSQL).NoSQL: Non-relational, flexible schema (e.g., MongoDB, Cassandra).
5. What are HTTP status codes?200: OK404: Not Found500: Internal Server Error

Front-End Development

1. What is the difference between HTML and HTML5? HTML5 introduced new tags like <article>, <section>, <audio>, <video>, and supports offline storage and multimedia.
2. What is the DOM? The DOM (Document Object Model) represents an HTML document as a tree structure where each node is an element.
3. What are CSS flexbox and grid?Flexbox: One-dimensional layout (row/column).Grid: Two-dimensional layout (rows and columns).
4. What are media queries in CSS? Media queries allow you to apply styles based on device properties like screen width (@media screen and (max-width: 768px)).
5. What is React Virtual DOM? React’s Virtual DOM is a lightweight copy of the DOM, used for efficient UI updates by minimizing direct DOM manipulation.

JavaScript

1. What is the difference between var, let, and const?var: Function-scoped, hoisted.let: Block-scoped, not hoisted.const: Block-scoped, cannot be reassigned.
2. What is asynchronous JavaScript? Asynchronous JavaScript (e.g., using Promises or async/await) allows non-blocking operations like API calls.
3. What is the purpose of closures? Closures allow a function to access variables from its outer scope even after the outer function has returned.
4. What are JavaScript frameworks commonly used in full-stack development?Front-end: React, Angular, Vue.js.Back-end: Node.js, Express.js.
5. What is CORS? Cross-Origin Resource Sharing (CORS) allows restricted resources on a web page to be requested from another domain.

Back-End Development

1. What is Node.js? Node.js is a JavaScript runtime built on Chrome’s V8 engine, enabling server-side scripting.
2. What is middleware in Express.js? Middleware functions handle requests, responses, or errors in Express.js applications.
3. What is the difference between monolithic and microservices architecture?Monolithic: Single codebase.Microservices: Decoupled, independently deployable services.
4. What is JWT? JSON Web Token is used for securely transmitting information between parties as a JSON object, often for authentication.
5. What are some popular backend frameworks?Node.js (Express.js, Nest.js)Python (Django, Flask)Ruby (Ruby on Rails)

Database

1. What is indexing in databases? Indexing improves database query performance by creating a data structure that allows quick data retrieval.
2. What is the difference between DELETE, DROP, and TRUNCATE in SQL?DELETE: Removes specific rows.TRUNCATE: Removes all rows, faster.DROP: Deletes the table itself.
3. What is ACID in database transactions? ACID stands for Atomicity, Consistency, Isolation, Durability, ensuring reliable transactions.
4. What is MongoDB, and how does it store data? MongoDB is a NoSQL database that stores data in JSON-like documents.
5. What are database relationships?One-to-OneOne-to-ManyMany-to-Many

DevOps and Deployment

1. What is Docker? Docker is a platform for containerizing applications, ensuring they run consistently in any environment.
2. What is CI/CD? Continuous Integration/Continuous Deployment automates code integration, testing, and deployment pipelines.
3. What is the purpose of load balancing? Distributes network traffic across multiple servers to ensure high availability and reliability.
4. What is the difference between a virtual machine and a container?VM: Full OS with hardware virtualization.Container: Lightweight, shares the host OS kernel.
5. What is Kubernetes? Kubernetes is an orchestration tool for deploying, scaling, and managing containerized applications.

Miscellaneous

1. What is the purpose of version control (e.g., Git)? Version control manages changes to source code, allowing collaboration and history tracking.
2. What are WebSockets? WebSockets enable full-duplex communication between a client and server in real-time.
3. What is GraphQL? GraphQL is a query language and runtime for APIs, providing more flexibility than REST.
4. What is CSRF and how to prevent it? Cross-Site Request Forgery is prevented by using tokens, same-site cookies, or header validations.
5. What is Webpack? Webpack is a module bundler that bundles JavaScript files and assets for deployment.