IDFC First Bank - GHOSTED - 4YOE - Senior Developer
Summary
I attended an on‑site interview for a Senior Developer role at IDFC First Bank in Bangalore, completed multiple rounds including DSA, LLD/DB design and system design, was told I passed, but later received no response.
Full Experience
Got a call for on-site interview at their Bangalore office on June 6th 2026. There were about 100 people attending the interview that day.
Round 1 - DSA - We are handed some prinouts of the question and asked to write the code in our computers and show the output. Some basic graph question was asked to me.
Round 2 - LLD + DB Design + Java + CI/CD - We were made to wait hours before this round. There were 2 people in the panel. Was asked to design DB for Airplane booking system and was asked few queries. Then there were questions about Interfaces in java, Java 8 features, etc. And finally few CI/CD and Kubernetes questions.
HR confirmed that I had passed the interview and the next round will be virtual.
Round 3 - (Re-scheduled 3 times and finally happened on July 10th) This round was with a Engineering Lead. There was one DSA question - print K th largest element of a BST, I had to write the code in my IDE. I wrote the function and explained the code to him but he wanted to test some inputs. When I said I have not written the functions to serialize and de-serialize the input/output and asked if I can write it, he just said lets move on (I am still unsure if he understood what I meant). Then he asked some questions about OAuth and JWT. Then we moved on to designing Rate Limiter, I had prepared it thoroughly from Hellointerview and explained him everything step by step following their framework. When I explained token-bucket algo and how I will use redis, he did not seem to fully understand things, then he got disconnected for 10 mins and asked me to repeat. The interview lasted for about 1 hr and 15 mins.
Now I have got no callbacks from HR (not even rejection) and it is about a month and have no hopes. I don't work in Bangalore and had to travel for this interview and it is disheartening to be ghosted. Avoid this company if you can.
Interview Questions (3)
Print Kth Largest Element in a BST
Given a binary search tree (BST) and an integer K, return the Kth largest element in the BST. The candidate is expected to write a function that traverses the BST and finds the element that would appear in position K if the tree were traversed in descending order.
Design a Rate Limiter
Design a rate‑limiting system that can control the number of requests a client can make within a given time window. The candidate discussed using a token‑bucket algorithm and storing tokens in Redis, explaining how the bucket refills and how request validation would be performed.
Design Database for Airplane Booking System
Create a relational database schema for an airplane booking system. This includes defining tables for flights, seats, bookings, customers, and related queries such as checking seat availability and retrieving booking history.
Preparation Tips
I prepared the Rate Limiter design thoroughly using the Hellointerview framework and reviewed token‑bucket algorithms and Redis integration. I also brushed up on Java 8 features, interfaces, and common DB design patterns for the airplane booking system.