Jane Street overhauls its coding interviews to test how candidates use LLMs
Jane Street – Our software engineering interviews are changing (a little)
Jane Street is trialing new onsite interview formats for campus candidates this summer, shifting away from pure code-writing toward software design, judging code quality and intent, and using LLMs to generate code. Most rounds stay traditional and LLM-free, and the firm stresses it doesn't expect candidates to have a polished agent workflow — just clear thinking about what the tools are good at and where they fall short.
As generating code has become arguably cheaper than ever, other parts of the job have come to matter even more: taste about what to build, choosing abstractions that last, and making sure what got built is actually correct, among other things.
- fernandotakai
so, i've gone through a bunch of iterations on how to interview in days of LLMs and i came up with a process that is quite good:
first, a coding problem that is solved live (right now, online) -- it's not a hard one and most LLMs can easily one shot it.
BUT: if you are not a senior developer, you need to do it without LLM, and if you are a senior+ and do it via LLM, the bar is super raised and now you need to explain in details everything the LLM wrote as if you wrote it yourself.
the main component here is to know if the candidate understands coding in general, understands problem solving and how to dive into an existing (although quite small) codebase. solving the problem is not really the goal -- in fact, most candidates we hired did not solve it 100%, but were able to understand and explain everything that they put it on code. this usually takes 1h30.
(we also ask the candidate to open a PR against the repo just to see if they know the basics of git -- you would be surprise how many people cannot do it).
the second is an architecture interview, where we build a system together BUT instead of doing the whole spec, miro board, whatever, we do it in more of a free way: we start with a really simple, MVP level, spec and we ask how the candidate would build it. then, we add another feature, and we ask how they would go for it. during this whole thing, i ask random questions like "why would you use x instead of y?" or "why do you prefer this approach?".
one important thing: we […]
- bluGill
Does it work? How do they know it works?
There are a lot of people telling you how they interview and why. Almost none of them have shown even the slightly indication that they are aware there there is scientific research on what works for an interview, much less that they apply it. They also are not showing any indication that they have done any testing - to see if their questions help hire better people.
If I said they could get equal results by picking resumes at random and hiring them without any other screening could they refute that? If so have they justified every part of their process or just one step that is useful and the rest they don't know?
- saghm
This is the third Jane Street-related thing I've seen on here this week after not seeing much about them that I can remember any time recently beforehand I'm aware of their use of OCaml and probably do other things that might be of interest to the HN community, but it seems like a lot in a very short time out of nowhere. Is there some sort of marketing push or something going on?
- floathub
This is a completely side comment, but I don't understand why stories about Jane Street keep making the front page day after day:
Today:
https://news.ycombinator.com/item?id=50467297
Yesterday:
https://news.ycombinator.com/item?id=50455394
Two days Ago:
https://news.ycombinator.com/item?id=50438261
It's a bit odd (?!).
- zerop
A friend recently got through Google after getting interviewed in Meta and several other companies. He said interview styles are changing in most places but there is no common pattern. Every company is taking their own custom approach. Some are giving open access to AI IDE, some are asking to not ask everything and monitoring what you ask. One company give access to LLM (probably custom) that would provide wrong code intentionally and candidate has to correct it.
- parthdesai
Pretty vague blogpost tbh. Apart from the fact that it's changing, it doesn't really describe much
- nphardon
the thought of going into an interview and getting asked to write code is a joke at this point. i haven't written more than a handful of lines in over a year. the interview should be related to the job.
- Surac
Code Interviews are a big waste of time for the employee and the employer. look what the human can bring to the table.