I applied through a staffing agency. I interviewed at Jane Street (London, England) in Dec 2025
Interview
1x screening call leetcode easy + 1x internal recuiter call + 1x onsite system design + 1x onsite leetcode medium~ish coding interview.
Overall it was a decent experience but I'll have to underline some points:
* One interviewer asked "You're originally from X?" this is considered discriminatory based on UK's Equality Act 2010.
* One of the interviewers couldn't quite read C++ which was a bit disappointing considering that I'm a C++ dev. I could have chosen the language accordingly.
* Asked to not to talk about the questions asked.
A- you don't get to do that without a contract,
B- It just helps friends of the employees to thrive on interviews.
* Onsite Interview taking whole day is costly (candidate has to take a day off) and tiring.
* There is a blanket policy of "not providing feed-back", which makes re-applying meaningless.
Interview questions [1]
Question 1
System design interview: file system design
Coding exercise: An immutable tree structure being hashed and compared to a remote via an API efficiently
It was a very quick and painless process. Recruiter very responsive, kind interviewers. High implementation and difficult problems, so failed onsite after 3 interviews and a Question and Answer Session.
Did not pass the initial coding round. I tried to explain my thought in details to the interviewer but failed to translate my thought into code. So far interviewer is very nice.
I applied online. I interviewed at Jane Street (New York, NY)
Interview
My experience interviewing at Jane Street was definitely challenging, but also surprisingly collaborative. Instead of focusing only on whether I could get the right answer quickly, the interviewers were much more interested in how I approached problems and explained my thinking. I worked through a few coding questions involving data structures and algorithms, and there were also some probability-style questions that tested logical reasoning. The interviewers were clearly very sharp, but they were also approachable and encouraged me to talk through my thought process the entire time. When I got stuck, they would sometimes guide me with small hints so we could keep exploring the problem together. Overall, it felt less like a typical high-pressure interview and more like a thoughtful technical conversation with experienced engineers.
Interview questions [1]
Question 1
“What is the expected number of coin flips needed to get two heads in a row?”