Advise- don't give interview, the process is notoriously poor, no transparency and takes around 30-45 days.

I attended online interview for Senior Java + Microservices Developer, processes involved 4 stages -

1. Codility test - MCQs + 2 simple coding question
2. L1 interview - Core technical with focus on Java basics, design patterns, concurrency, database and microservices.

L2 - similar to L1 but was focused on business terminology ( financial services basic concepts related to cards and payments, trade finance difft standards like ISO 8583, ISO 20022, and SWIFT MT

L3- Managerial. Basic and simple, focused on why you want to join the Citi Bank.

I cleared all the rounds and got confirmation but they said that there is some budget issue though at very beginning I had communicated the expected CTC. They rejected my profile in business review phase saying that they got better candidate.

HashMap and Concurrent HashMap working

Design patterns

Microservices patterns and architectural constraints

Database basics, and simple SQLs

LinkedList algos etc