Compiler Engineer

Jane Street is hiring a Compiler Engineer in London, United Kingdom. Level rates it ; you can apply on Jane Street.

Level's read on this job

Uses AI ●●○○ is how Level rates this role: an ordinary role that requires AI tools.
Tools and skills the posting cites include Llvm, Gdb and Lldb.
Level classifies it as a senior role.
Level lists 216 other open roles at Jane Street.

AI in this role

Develop code optimizations and features for the OxCaml compiler while utilizing AI coding assistants to accelerate delivery.

LlvmGdbLldb

compiler-designcode-generationc-plus-plusocaml

About the Position

We are looking for an experienced software engineer to work on code generation in the OxCaml compiler, which is open source. OxCaml is Jane Street’s variant of the OCaml language, equipped with powerful features for high-performance and parallel programming, with data race freedom guarantees.

This role involves the full cycle of identifying new optimisations, coding, testing, benchmarking and deployment. There will be the opportunity to work across a wide variety of intermediate representations, including CPS, SSA and maybe even Sea of Nodes. This role will also allow you to interact with many different groups and exceptional individuals across Jane Street worldwide.

About You

The ideal candidate will be super productive: fast at writing correct code, willing to use AI assistance to get changes to production faster and experienced with debuggers (e.g., lldb, gdb) and low-level Linux tools. Having knowledge of x86-64 and AArch64 architectures at the assembly language and architectural level is a plus.

We are happy to consider candidates with experience on any compiler toolchain, although knowledge of LLVM would be useful. No knowledge of the OCaml or OxCaml languages is required–we can teach you what you need to know.

We are particularly interested in candidates who have proven experience managing a team of developers, and who would enjoy doing that alongside their normal technical work. Fluency in English is required.

If you're a recruiting agency and want to partner with us, please reach out to agency-partnerships@janestreet.com

How we rate this

Compiler Engineer at Jane Street rates 45 out of 100 for how much of the daily work is AI. That makes it Uses AI (AI Level 2 of 4). The level is about AI in the job, not seniority.

Classification

Uses AI. An ordinary role that requires AI tools.

●●●● Builds AI80 to 100
●●●○ Works on AI60 to 79
●●○○ Uses AI40 to 59
●○○○ Little AI0 to 39

Levels come from how often the tools, models and workflows of the role are named in the posting itself. Read the description and count the AI tools, models and workflows it names.

Key facts

Compiler Engineer is an open job at Jane Street.
Level rates this role AI Level 2 of 4: Uses AI.
The role is based in London, England, United Kingdom.
The job was posted on June 26, 2026.
Seniority: senior.
Applications are handled by Jane Street. Apply on Jane Street

Prepare for this job

Built from this posting and from similar jobs on Level.

Skills and AI tools this role asks for

Compiler DesignCode GenerationC Plus PlusOcamlLlvmGdbLldb

Questions you could be asked

Tell me about a project where compiler design was part of your work. What did you do?
Tell me about a project where code generation was part of your work. What did you do?
Tell me about a project where c plus plus was part of your work. What did you do?
Tell me about a project where ocaml was part of your work. What did you do?
Walk me through how you've used Llvm in your day-to-day work.

Adapt your resume

List these exact terms on your resume: Compiler Design, Code Generation, C Plus Plus, Ocaml, and Llvm. An applicant tracking system matches the wording, not the idea.
Attach one line of real, concrete experience to at least one of them. A tool named with nothing behind it rarely survives a human read.
Put the AI tool in a bullet point about what you did, not just in a skills list. This role treats it as a required part of the job.

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