After a 5th recruiter reached out to me, decided to have a chat with them. After a chat with external recruiter, next step is 30 minute call with general ML questions and questions about your projects. Then comes a take-home assessment, limited to 150 minutes, which covers generic data analysis and model building. It favours Spark framework, but still doable if you don't have any experience with it. Next step was slightly botched by them. They told me there will be a one round of 1-2 hours. When asked what sort of interview was it, there was no information given aside the generic "we will assess you technical knowledge, machine learning and data engineering skills". Turned out to be an ML system design round (Design system X). After that round I was informed that there will be a second round right after (which wasn't mentioned before but was still in the 2h timeframe). In this round the interviewers were supposed to ask me Spark questions, but couldn't since there were none on my CV, so we chatted a bit about random data processing stuff and NoSQL. After that there is supposed to be an HR round, but they decided not to proceed.

My experience with PayTM labs has been extremely negative and frustrating. There was a machine learning phone screen at the beginning, then a take home data and machine learning challenge (for a week), then an in-person onsite technical interview with 4 people and then an HR interview, all of these took place almost in the span of a month. On the onsite day, I was explicitly told that I did great in the take home challenge and also in the onsite itself, and was certainly expecting an offer. The tech people were really nice and friendly, and knowledgable. Then came the HR interview (the following day) and there were 2 HR people asking me about how I liked the team, the interview process etc, and were also complimenting me on my interview performance. At the end, they told me that the next thing was a face to face meeting with the CEO, they were gonna schedule that and get back to me with the date and time. I was eagerly waiting for that. I followed up with HR twice and there was no reply even out of courtesy, and then 3-4 days later all of a sudden the recruiting agency (whom I applied through) got back to me and to my utter surprise told me that they decided not to proceed - without any concrete reasons, which means on the HR day, they literally lied to me about the CEO interview. This is a mystery to me what possibly went wrong, and this was by far the worst interview experience I ever had. They should show a greater level of professionalism and honesty at least towards a candidate who has gone through 4 rounds of interviews and assessments and dedicated his time towards the interview process for almost a month ! Very disappointing - I was almost hoping for my dream job. Expected more from them honestly. (Once again, I liked the technical people and the tech team in general, but didn't like the mystery that went with HR at all, sorry)