Initial screening round

There were 2 OA questions, don't remember what was asked. But AFAIK they were questions around prioirty queue

L1 Interview

I was asked questions about my current project. They ask questions about the architecture, the tech stack used in the project. The objective would be to understand how well do you know your project and if you understand how tech decision are made. This is very important. Considering one scenario in my interview, I was asked what scaling policies were in place for a particular microservice in my project and explain why.

Post that I was asked to design instagram with basic feature, not too much of HLD and LLD, they want to understand how you would pick your database, design your API's and schema.

I was also asked to implement max heap

L2 Interview

I was asked to introduce myself and talk about the project I am working on. Post that I was asked to design a notification banner system like thing for a apartment. Something like the board you see in stock markets where the stock price keep rotating. The question would be very open ended. It is upto you to ask the right questions and design the system.

I was also asked to design class, API and db design for the same. Post that the question was extended for various scenarios.

L3 Interview, CTO round

L3 and CTO round are almost the same. They check your behvaioural aspect, passion for technology, adaptability under pressure and other things.

Result: Cleared all the rounds

Tips

1. Following SOLID is must
2. Having experience in TDD is good to have
3. Have a good knowledge about your current project
4. Learning to select the correct components (HLD) for a given problem and also able to defend it. For eg: i chose nosql over sql for instagram design. Since i did not need transactional capabilites and no sql is schemaless better flexibility.