I recently went through the interview process for a Staff Backend Engineer role at JioStar. I appeared for 2 rounds and was rejected in the second round.
Sharing my experience in case it helps others preparing for similar roles.
1) HLD + LLD Round
Problem: Recommendation System
I was asked to design a recommendation system that would provide:
Current/Continue Watching — shows that the user has already started watching and can resume. We discussed keeping these entries only for a certain period, e.g. up to X days old.
Recommended Shows — a list of shows recommended based on different factors such as:
User's location
Previous watch history
Other recommendation factors
I first clarified the requirements and then designed the overall system, covering the major components, data flow, and storage.
The interviewer then went deeper into implementation details and asked questions around:
Client-side caching
Database selection and data modeling
How current/continue-watching data would be stored and retrieved
How recommendations would be generated
Service interactions
Other HLD/LLD trade-offs
Verdict: Clear
2) AI-Assisted Coding Round – 90 mins
Problem: Config Management Service / Library
The problem was to design a configuration management solution.
Initially, I interpreted it as a distributed configuration management service, similar to AWS AppConfig. During the discussion, I understood that the expected solution was actually a client-side library/SDK that would be deployed along with the application and manage configuration locally. The interviewer then asked me to implement the design using an AI coding assistant.
The API was along the lines of:
getConfig(configKeyName, Map<String, String> params)
where the configuration could have rules based on parameters such as:
Country: India
Device: Android
The interviewer focused on priority handling for configuration rules — specifically, how to resolve the configuration when multiple rules match the request and how precedence should be determined.
Verdict: Rejected
Please up-vote, to motivate me to upload my other interview experiences :)