Software Engineer

About this role

Jane Street seeks software engineers to build trading systems, infrastructure, and tools across the firm using primarily OCaml and Python. You'll solve critical problems in finance while working with a team that values functional programming, open source contributions, and continuous learning.

What you'll do

• Design and implement systems serving trading desks, accounting, and other business-critical functions
• Build foundational infrastructure including network monitoring and risk models
• Develop solutions in OCaml (primary) and Python (data analysis, ML, research)
• Contribute to and maintain open source projects
• Collaborate across teams to solve real-world problems
• Write statically-typed, functional code at scale

What they're looking for

• Strong programming fundamentals and problem-solving ability
• OCaml or functional programming experience (or willingness to learn)
• Python for data analysis and machine learning
• Systems design and infrastructure development
• Software architecture and code quality
• Open source contribution experience
• Intellectual curiosity and collaborative mindset
• Quick learning ability across tech stacks

Benefits

• Work on high-impact trading and financial systems
• Access to cutting-edge technology and open source projects
• Mentorship from experienced functional programming experts
• Exposure to machine learning and data analysis at scale
• Opportunity to contribute to open source (Mercurial, OCaml compiler, OPAM)
• Collaborative culture that values learning and asking questions

Likely interview questions

• Tell us about a complex problem you've solved and walk us through your approach.
• What experience do you have with functional programming, and how do you think about it?