Jane Street Software Engineer Interview Guide

Jane Street runs one of the most collaborative software engineer interviews in tech, despite a public reputation built on brain-teasers and mental math. Most of the loop centers on extending a single coding challenge as your interviewers layer on new requirements, and they care more about how cleanly you build and explain your work than how far you get. You're evaluated on how you build and communicate in every round.

This guide breaks down each stage of the Jane Street software engineer interview, what interviewers look for, and how to prepare with real example questions, actionable tips, and resources.

Jane Street software engineer interview process

The Jane Street software engineer interview runs in two main parts: a remote technical screen and a full-day onsite. Senior candidates also have a project discussion on the onsite day. Unlike most tech loops, where each round is a fresh question, Jane Street tends to develop one coding solution across rounds as interviewers layer on new requirements.

Here's what the process can look like:

• Recruiter conversation: A brief call that sets expectations and explains the collaborative, hints-allowed format
• Technical screen: A roughly 60-minute remote coding round with one interviewer, working through a single challenge in your strongest language
• Onsite coding rounds: A full day of three to four long coding rounds, usually around 70 minutes each and most with two interviewers
• Project discussion (senior and up): A conversational round on a past technical project, centered on the reasoning behind your decisions

Recruiter conversation

The Jane Street recruiter call is a 20-30 minute conversation that sets expectations before the technical rounds. Expect questions about your background, why you want to join Jane Street, and logistics like location and timing.

Jane Street considers every application across its open roles, so the recruiter may route you toward a different team than the one you applied to. More experienced candidates sometimes have an additional non-technical call to discuss what they're looking for.

Technical screen

Jane Street's SWE remote technical screen is roughly 60 minutes with one interviewer, where you work through a coding challenge together. You'll write real, runnable code in the language you know best.

The interviewer starts you on a base solution, then adds requirements on top, so the round centers on how you extend and explain your own code. Expect a collaborative tone; interviewers offer hints if you stall and expect you to ask clarifying questions as you go, and accepting a hint isn't seen as a bad sign.

Interviewers look for:

• Clean, correct code: Whether your implementation is clear and obviously correct
• Communication: How clearly you talk through your reasoning while you code
• Clarifying questions: Whether you surface assumptions and edge cases before committing to an approach
• Extensibility: How well you adapt your solution as new requirements get added
• Collaboration: How you respond to hints and work with the interviewer

Recently asked questions

The screen is built around one challenge you develop across the full round, so expect to go deep on a single prompt. Here's an example of a prompt reported by a recent candidate:

• Implement Connect Four, then a generalized Connect K. How would you model the board and game state?
• How would you extend your solution as the interviewer adds new constraints?

Onsite coding rounds

The Jane Street onsite is a full day of three to four long coding rounds, usually around 70 minutes each, typically run with two interviewers. One interviewer typically leads while the other observes or adds a different angle, which keeps the round closer to a structured working session.

Each round tends to build on a single solution as requirements get layered on. Despite Jane Street's association with functional programming and OCaml, expect challenges to map naturally to object-oriented code.

Interviewers evaluate:

• Incremental design: How you structure a solution so it absorbs new requirements without a rewrite
• Code clarity: Whether your code stays clean and correct as it grows
• Reasoning out loud: How you explain tradeoffs while you build
• Handling hints: How you incorporate a nudge and keep moving
• Depth: Whether you develop the challenge thoroughly across the round

Recently asked questions

Here are real Jane Street coding questions, from candidate reports and Jane Street's own materials:

• Implement a Merkle tree. How would you traverse or search it as the structure grows? How would you build more functionality onto your initial implementation?
• Implement Tetris, modeling the game state, the pieces, and the rotation logic. How would you represent the game state? How would you handle rotating pieces?
• Write a memoized version of an expensive function, then extend it to evict the least recently used entries once it reaches a size limit. How would you make both lookups and eviction O(1)?
• Given one class interface, implement it using a second class interface. How would you apply the same approach to a general tree structure?

Project discussion (senior and up)

The Jane Street project discussion tests how clearly you can reason about your own technical decisions. Senior and staff candidates have this conversational round on the onsite day, built around one past project. You'll walk through it while interviewers ask questions about your decisions, like why you chose a given design and what was happening in the systems next to yours.

The tone stays casual, but follow-up questions go deep. Come in with a few projects you can discuss, since interviewers may steer you toward one you haven't polished, and being candid about what you don't know matters more than a scripted answer.

Interviewers look for:

• Decision rationale: Why you made specific design and tradeoff choices
• Systems awareness: How well you understand the systems adjacent to your own work
• Honesty: Whether you can name what you didn't know or didn't own without guessing
• Ownership: How directly you contributed to the project you discuss
• Clear reasoning: How you explain complex technical work in conversation

Recently asked questions

The project discussion centers on one project and the decisions behind it, so expect a single prompt that opens into deeper follow-ups. Here's an example reported by a recent candidate:

• Walk me through a technical project you've worked on. Why did you make that design decision? Why didn't you take a different approach?
• What was happening in the adjacent system your work depended on?
• How would you design it differently if concurrency were a concern?

How to prepare for the Jane Street software engineer interview

1. Practice implementation-heavy data structures and algorithms: Focus on writing clean, correct implementations of data-structure challenges, since the rounds don't test quant math or brain-teasers.
2. Practice talking while you code: Narrate your reasoning, surface assumptions, and keep explaining as you extend your solution.
3. Get comfortable building on your own code: Expect each round to add requirements to a single solution, and practice adapting a design as constraints grow.
4. Prepare one or two projects in depth for the senior project discussion: Know the reasoning behind your design decisions and what happened in the systems around yours. Avoid scripting a polished speech, since interviewers may steer you to a project you haven't polished.
5. Sharpen your fluency in one language: Practice implementing data structures in the language you'll use until the syntax is automatic, so you can focus on design and communication.
6. Practice with mock interviews: Run timed, collaborative mock interviews and get feedback from an expert coach so the build-and-explain format feels natural.

About the Jane Street software engineer role

Jane Street software engineers build production systems in OCaml regardless of their background, so the role rewards general programming ability over any specific language going in. Jane Street builds almost everything in OCaml, its primary language, and runs the largest OCaml team in any industrial setting, with Python as a common second language. Most engineers join with little or no OCaml or functional programming experience and learn it on the job through an apprenticeship-style rotation in the first year or so.

Day to day, engineers work across trading systems, infrastructure, and internal tooling, much of it low-latency, supported by in-house systems for code review, performance tracing, and web UIs. New hires learn Jane Street's tools and languages through internal courses and team rotations before settling onto a team.

Additional resources

• Software Engineering Interview course
• SWE Behavioral Interview course
• SWE Coding Questions course
• Real Jane Street software engineer interview questions
• Real Jane Street software engineer interview experiences
• Jane Street company page
• Preparing for a Jane Street software engineering interview
• What to expect in a Jane Street interview

FAQs about the Jane Street software engineer interview

Does the Jane Street software engineer interview use standard coding challenges?

Jane Street's coding rounds use open-ended challenges you develop and extend across a full round. Jane Street states plainly that its SWE interviews don't involve mental math, math-olympiad questions, or logic puzzles, so the standard algorithm puzzles common at other companies are largely absent. You'll write real code in the language you know best, and interviewers expect you to ask questions and accept hints.

Prep resources that emphasize probability, mental math, or OCaml are usually describing Jane Street's trading and quantitative roles; those topics don't appear in the SWE loop, which centers on clean, correct implementation and clear communication.

Does the Jane Street software engineer interview include a system design round?

Jane Street's software engineer loop doesn't typically include a separate system design round. The onsite centers on extended coding challenges, and senior candidates complete a project discussion focused on past technical work. You'll still apply core system design principles as you structure and extend your solutions in those rounds.

Does the Jane Street software engineer interview include a Linux or systems round?

The general Jane Street SWE loop centers on collaborative coding and doesn't include a dedicated Linux or systems-internals round. Jane Street's Linux Engineering and infrastructure tracks run a separate process that can include a Linux scripting and debugging round, so match your prep to the role you applied for.

How long is the Jane Street software engineer interview process?

The Jane Street software engineer interview process typically takes 3-4 weeks. A recruiter usually responds within a few days of your application, and Jane Street aims to give feedback within about a week of each round, so checking in after 10 days of silence is reasonable.

How much does a Jane Street Software Engineer make?

Here are the reported compensation figures for Jane Street software engineers, according to Levels.fyi (mid-2026):

• Entry level (L1): around $380K total, with a base near $260K and most of the rest as cash bonus
• Median across levels: around $350K total
• Top reported package: around $587K

These figures are self-reported and based on small samples, so treat them as directional. Jane Street salaries are among the highest in tech and skew heavily toward cash; equity is a small slice of the package and the annual bonus drives most of the variation. At senior levels, some pay is deferred or locked through longer-term structures.