Lokal Full Stack Developer Interview: Rounds, Questions and Preparation

What the job involves

A full stack developer at Indian unicorns or high-growth startups builds and ships end-to-end features, from responsive React or Vue frontends to Node.js or Django backends and database schemas. You will work in small agile teams, often owning a feature from design to deployment, and iterate quickly based on user feedback and metrics. Expect to touch cloud services, CI/CD pipelines, and basic system design to support fast scaling.

Role and technical knowledge

1. 1

   What happens when you type a URL in the browser and press enter, focusing on the full stack?

   Cover DNS, TCP, HTTP request, server-side routing, database query, and rendering. Mention how frontend and backend interact via APIs.

2. 2

   How would you design a REST API for a hyperlocal content feed like Lokal's?

   Outline endpoints for posts, users, and comments, use proper HTTP methods and status codes, and discuss pagination and caching.

3. 3

   Explain the difference between SQL and NoSQL databases and when you would use each in a startup.

   Compare schema flexibility, scaling, and consistency. Give examples like PostgreSQL for transactions and MongoDB for unstructured feeds.

4. 4

   What is the virtual DOM in React and why does it matter for performance?

   Explain diffing and efficient updates. Mention keys in lists and avoiding unnecessary re-renders.

Practical scenarios

1. 5

   You are building a feature that shows local news in a user's language. How would you handle multilingual content on the frontend and backend?

   Discuss i18n libraries, storing translations, and API design for language parameters. Mention fallback and caching strategies.

2. 6

   A page is loading slowly. How do you debug and improve performance across the stack?

   Cover browser dev tools, network waterfall, database indexing, and code splitting. Suggest measuring before optimizing.

3. 7

   How would you implement user authentication and authorization for a mobile-first web app?

   Mention JWT or session-based auth, secure storage, HTTPS, and role-based access control. Discuss refresh tokens and logout.

4. 8

   You need to deploy a full stack app quickly for a hackathon or MVP. What is your approach?

   Talk about using platforms like Vercel or Heroku, environment variables, and a simple CI/CD pipeline. Prioritize speed and basic monitoring.

Behavioural and HR

1. 9

   Tell me about a time you worked in a team to build something from scratch.

   Use STAR method. Highlight your specific contribution, collaboration, and how you handled disagreements.

2. 10

   Why do you want to work at a high-growth startup like Lokal instead of a large MNC?

   Show understanding of startup pace, ownership, and impact. Connect to your desire to learn broadly and ship fast.

3. 11

   Describe a technical challenge you faced and how you overcame it.

   Focus on the problem, your debugging process, and the outcome. Mention what you learned and how you would apply it.

4. 12

   How do you prioritize tasks when you have multiple deadlines?

   Explain a framework like impact vs effort, communication with stakeholders, and using tools like Trello or Jira.

Problem solving and coding

1. 13

   Write a function to find the first non-repeating character in a string.

   Use a hash map to count frequencies, then iterate to find the first with count 1. Discuss time and space complexity.

2. 14

   Given an array of integers, return indices of two numbers that add up to a target.

   Use a hash map for O(n) time. Explain why brute force is O(n^2) and how to optimize.

3. 15

   How would you reverse a linked list iteratively and recursively?

   Show both approaches, discuss pointer manipulation, and mention edge cases like empty list or single node.

4. 16

   Design a simple URL shortener. What database schema and API would you use?

   Cover hashing or base62 encoding, mapping short to long URL, and handling collisions. Mention read-heavy optimization.