I applied through a recruiter, and the process took two weeks.

I got a call from the recruiter via LinkedIn. First, he scheduled a call to know more about my profile. He asked a few basic questions on scalability, multithreading, and dependency injection, etc. Then he gave a HackerRank coding challenge that needed to be finished within 72 hours (three days). After that, they scheduled a technical round with one of their engineers. If you clear it, there is a CTO round. In my case, I was rejected in the technical round because the interviewer asked too many theoretical questions.

HackerRank Round had one easy and one medium-level question, and a few multiple-choice questions on SQL queries and Java. One question was to calculate the time difference. I don't remember the second question, but it was a medium-level one.

Technical Round 1 covered a few project-level questions. The interviewer asked what SOLID is and about the "I" in SOLID, the difference between Spring and Spring Boot, the difference between field injection and constructor injection along with their advantages and disadvantages, how to achieve scalability, and how to handle multiple requests in REST. They asked how GC works in Java. You should read and understand it completely so that you can elaborate. Other topics included what a REST API is, what GET, POST, PUT, and DELETE are, the difference between PUT and PATCH, and when to use each. If the wait time is long in a REST API, how can you improve it? The interviewer asked how to design a microservice and what its advantages are, and gave a scenario where an online shopping portal has an items catalog and a payment service, asking how a REST request will proceed.

There were a few MySQL query-based questions, such as being given items with a category and finding a SQL query to find items based on category, and how to make this query faster, like adding an index on the category. Now the query changes to find by category and price; how can you add an index here, how will you write the query, and which column will be scanned first? You should read how a multiple-column query works. Additional topics included how Spring security works, what a JWT token is, how it works, and how authentication works in Spring. Finally, the interviewer asked what Spring WebFlux is, the difference between Spring WebFlux and Spring MVC, and about blocking versus non-blocking.