Tech Mahindra Full-Stack Developer Interview Questions

Welcome to the detailed interview guide for Tech Mahindra. This page contains specific, extracted interview questions with direct resource links to help you prepare effectively.

1. Coding & Algorithms

Tech Mahindra evaluates your problem-solving skills using Data Structures and Algorithms. Below are highly frequent questions asked by Tech Mahindra.

Detailed Data Structures & Algorithms Questions

1. Reverse a String / Array (Strings / Two Pointers)
   • Question: Write a function that reverses a string. The input string is given as an array of characters.
   • Resource: LeetCode 344 - Reverse String
2. Valid Palindrome (Strings)
   • Question: Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.
   • Resource: LeetCode 125 - Valid Palindrome
3. Find the Duplicate Number (Arrays)
   • Question: Given an array of integers nums containing n + 1 integers where each integer is in the range [1, n] inclusive, find the duplicate number.
   • Resource: LeetCode 287 - Find the Duplicate Number
4. Detect Loop in Linked List (Linked List)
   • Question: Given head, the head of a linked list, determine if the linked list has a cycle in it.
   • Resource: LeetCode 141 - Linked List Cycle
5. Fibonacci Number (Math / DP)
   • Question: Find the Nth Fibonacci Number. Commonly asked in entry-level screening.
   • Resource: LeetCode 509 - Fibonacci Number

2. Core Full-Stack Technologies

As a Full Stack Developer, Tech Mahindra expects you to have a deep understanding of both frontend and backend ecosystems.

Detailed Frontend Questions (React / JavaScript)

1. Virtual DOM & Reconciliation
   • Question: Explain how React's Virtual DOM works and describe the Diffing algorithm.
   • Resource: React Docs - Reconciliation
2. Event Delegation & Bubbling
   • Question: What is event bubbling and capturing in JavaScript? How does Event Delegation improve performance?
   • Resource: JavaScript.info - Bubbling and capturing
3. Promises and Async/Await
   • Question: Write a function to execute an array of Promises sequentially (one after another).
   • Resource: MDN - Using Promises
4. Custom Hooks Implementation
   • Question: Write a custom useDebounce hook that delays invoking a function until after wait milliseconds have elapsed.
   • Resource: useHooks - useDebounce

Detailed Backend Questions (Node.js / Express / DB)

1. Event Loop in Node.js
   • Question: Explain the phases of the Node.js Event Loop. What is the difference between process.nextTick() and setImmediate()?
   • Resource: Node.js Docs - Event Loop
2. Database Indexing & Optimization
   • Question: How do database indexes work under the hood (B-Trees)? When should you NOT use an index?
   • Resource: GeeksForGeeks - Indexing in Databases
3. JWT vs Session Authentication
   • Question: Explain the pros and cons of using JSON Web Tokens (JWT) vs stateful Session cookies for authentication in a distributed system.
   • Resource: Auth0 - JWT vs Sessions
4. API Rate Limiting
   • Question: How would you implement rate limiting for a REST API using Redis?
   • Resource: Redis - Rate Limiting Pattern

3. Architecture & System Design

System design is crucial, especially for mid-to-senior level roles at Tech Mahindra.

Detailed System Design / Architecture Questions

1. Monolith vs Microservices
   • Question: Explain the scenarios where a monolithic architecture is preferred over microservices, and vice versa.
   • Resource: Martin Fowler - Microservices
2. Database Schema Design
   • Question: Design a normalized database schema for a Library Management System.
   • Resource: Lucidchart - ER Diagram Tutorial
3. Caching Strategies
   • Question: When would you use Write-Through vs Write-Behind caching?
   • Resource: AWS - Caching Strategies

4. Behavioral & Culture

• STAR Method: Always answer behavioral questions using Situation, Task, Action, Result.
• Why Tech Mahindra?: Research Tech Mahindra's core values (e.g., Amazon's Leadership Principles, Google's "Googliness", or TCS's client-first approach).
• Resource: How to answer Behavioral Questions

5. Latest 2026 Interview Trends

• Cloud Migration: Questions frequently revolve around migrating legacy monoliths to AWS/Azure, utilizing containerization (Docker/Kubernetes).
• Security & DevSecOps: Expect questions on OWASP Top 10, securing APIs with OAuth2/OIDC, and automated CI/CD pipeline security.
• Modern JavaScript: Extensive focus on TypeScript adoption, strict typing, and migrating large codebases from JavaScript to TypeScript.
• Resource: OWASP Top 10 Web Application Security Risks