Licious Backend Engineer Interview: Rounds, Questions and Preparation

What the job involves

Backend engineers at Indian unicorns and high-growth startups build and maintain the server-side systems that power consumer apps, internal tools, and data pipelines. Day to day, you write APIs, design database schemas, debug production issues, and optimize for scale and latency under tight deadlines. In a food-tech company like Licious, this often means handling order management, inventory sync, delivery routing, and payment integrations.

Role and technical knowledge

1. 1

   What happens when a user places an order on a food delivery app from the backend perspective?

   Walk through API call, order validation, inventory check, payment gateway, database write, and notification service. Mention idempotency and handling failures.

2. 2

   Explain the difference between SQL and NoSQL databases. Which would you use for a product catalog and why?

   Compare schema flexibility, scaling, and consistency. For a catalog with varied attributes, NoSQL like MongoDB can work, but SQL is fine for strong consistency and joins.

3. 3

   How would you design a rate limiter for an API endpoint that gets 10,000 requests per second?

   Discuss token bucket or sliding window, using Redis for distributed counters, and returning 429 status. Mention trade-offs between accuracy and memory.

4. 4

   What is the difference between horizontal and vertical scaling? When would you choose one over the other?

   Horizontal adds more machines, vertical adds more power to one machine. Startups prefer horizontal for cost and fault tolerance, but it needs stateless services.

Practical scenarios and problem solving

1. 5

   You deploy a new API version and suddenly order creation fails for 10 percent of users. How do you debug?

   Check logs for errors, roll back if needed, reproduce with specific user data, and verify database migrations. Mention monitoring tools and canary deployments.

2. 6

   A delivery partner app shows stale order status. How would you fix this?

   Investigate caching layer (Redis TTL), database read replicas lag, and websocket push. Suggest cache invalidation or event-driven updates.

3. 7

   You need to store 1 million order records per day and query them by date and customer ID. How would you design the schema?

   Use a partitioned table by date, index on customer_id and created_at, and consider archiving old data. Mention read replicas for heavy read traffic.

4. 8

   Your service calls a third-party payment gateway that is slow. How do you prevent it from slowing down your entire system?

   Use timeouts, circuit breakers, and async processing with a queue. Retry with exponential backoff and fallback to a secondary gateway if possible.

Behavioural and teamwork

1. 9

   Tell me about a time you worked in a team to build something under a tight deadline.

   Use STAR method. Focus on your specific contribution, how you prioritized, and what you learned about communication.

2. 10

   Describe a situation where you made a mistake in code that caused a problem. How did you handle it?

   Show ownership, quick acknowledgment, and a fix. Emphasize what you changed in your process to prevent recurrence.

3. 11

   How do you handle feedback from a senior engineer who rewrites your code?

   Show openness to learning, ask clarifying questions, and focus on the code not the person. Mention you review the changes to improve.

4. 12

   Give an example of a time you had to learn a new technology quickly for a project.

   Pick a concrete example, describe your learning approach (docs, tutorials, small prototype), and how you applied it successfully.

HR and company fit

1. 13

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

   Show comfort with ambiguity, fast pace, and broad ownership. Mention specific interest in food-tech or supply chain if relevant.

2. 14

   Where do you see yourself in three years as a backend engineer?

   Align with growing into a senior engineer who can own services end-to-end, mentor juniors, and contribute to system design.

3. 15

   How do you prioritize when you have multiple tasks - a bug fix, a feature, and a code review?

   Mention impact: production bug first, then unblock teammates via review, then feature. Communicate with your manager if unsure.

4. 16

   What do you know about our engineering culture or tech stack?

   Research the company's blog or job posts. Mention use of microservices, cloud (AWS/GCP), and any open-source contributions if known.