Interview Prep 2026
Crack the Node.js & Express interview — no fluff
40 Node.js
& Express
Questions
The most frequently asked Node.js & Express questions in 2026 interviews — event loop, async patterns, REST APIs, middleware, authentication, security, and deployment. Curated from real interviews at top companies.
"Node.js interviews don't just test if you've built a server — they test if you truly understand
the event loop, non-blocking I/O, and how to ship production-grade APIs that scale."
— The Boring Education Team
40
Questions
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Core topics
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2026
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40 Node.js & Express Interview Questions · 2026
02
Top 10 Must-Know Questions
Event Loop, Async, REST APIs & Middleware
Event Loop
async/await
Promises
Middleware
REST APIs
Authentication
CORS
Clustering
WebSockets
Rate Limiting
MongoDB / Mongoose
Socket.IO
GraphQL
Docker / Heroku
Security
01.
What is Node.js and how does it handle asynchronous operations?
02.
Explain the event loop in Node.js and its significance in managing concurrency.
03.
What is middleware in Express and how do you use it to handle requests?
04.
Explain the difference between blocking and non-blocking I/O with an example.
05.
How do you implement error handling in an Express application?
06.
Explain Promises and
async/await
— how they improve async code.
07.
What is CORS, why is it important, and how do you enable it in Express?
08.
How would you implement authentication in a Node.js & Express app?
09.
Explain the concept of clustering in Node.js and how it improves performance.
10.
What are RESTful API principles? How do you design one using Express?
Get all 40 questions with full answers. The complete list covers the
event loop deep-dive, Promises vs callbacks, session management, file uploads, GraphQL integration,
WebSockets, rate limiting, load balancing, microservices, security vulnerabilities, testing, and deployment
— all with code examples and real-world context.
All 40 Questions + Detailed Explanations 🚀
Code examples · Best practices · Common pitfalls · Interview tips · Real-world
applications
Practice all 40 questions and track your progress — completely free.
→ Practice All 40 Node.js Questions Free
Practice all 40 questions and track your progress — completely free.
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