I interviewed for TikTok in October 2021. There were three rounds of technical interviews, described as follows:

• Round 1: Coding interview. After a brief introduction, I was asked two coding questions to be solved in one hour. The interviewer was good; he made me quite comfortable, and the session was interactive. I solved both questions, and he did help me a bit with the second one. Result turnaround time: 24 hours.

• Round 2: System design + projects worked on so far. Result turnaround time: 24 hours.

• Round 3: Last round with a lead engineer. It was a mix of a culture fit interview, technical questions, system design, and coding. Result turnaround time: 1 week.

I did well in the interviews technically, and I still wonder why I was rejected. I totally respect the company's decision, but I'm disappointed that I was not given any feedback so that I could work on the points, if I found them to be valid. I only received an automated rejection email.

All the coding questions asked were available on LeetCode. It would be unfair to expose the exact questions, so I'll be summarizing the topics covered in each round.

Round 1: Trees and a math problem. These were medium-difficulty questions from LeetCode.

Round 2: System design plus projects worked on so far.

Questions covered distributed systems, best practices, unit and integration testing, transaction management, and common problems faced in a distributed environment. Some of these questions were abstract and open-ended; it helps if you can give examples when answering.

Round 3: Culture fit questions involved designing some features of a real-world system like Twitter, databases, and designing a cache with special features. We had to write pseudocode for these.