The work at Jane Street is technologically intense, and the systems we build play an essential role in everything we do.
The scope of the systems we build is large — billions of dollars worth of transactions flow through them every day — but the group behind them isn’t. That means that each person has the opportunity to make a substantial impact.
We organize our work into small, project-oriented teams, each with the independence and responsibility to make decisions that impact the future of the firm. That makes it easier to see how the business works from end to end, and how you can contribute.
It’s no secret that we’re big believers in functional programming, and use OCaml, a statically typed functional language, as our primary development platform. Jane Street’s technology group is small by design, which means we need to maximize the productivity of each person we hire. We believe functional programming helps us do that. But it’s not about productivity alone: programming in a rich and expressive language like OCaml is just more fun.
At Jane Street, functional programming isn’t a tool we reserve for some special set of problems. From systems automation to trading systems, from monitoring tools to research code, we write everything that we can in OCaml. We think it’s a tool that works well across a wide spectrum.
We’re also happy to spend time and money on making it easier for the people here to get things done. This ranges from big projects, like the work we do on development tools (e.g. Iron, our in-house code review and release management system, and Merlin, a tool for providing IDE-like features for OCaml), to little touches, like getting people whatever crazy keyboard will help them get their work done most comfortably.
Like almost every technology operation, we rely on tons of open source software in our daily work. We also believe open source should be a two-way street. From committing patches to the Linux kernel to publicly releasing some of our most significant projects, we’re constantly looking for ways to share our work with the community. You can find a bunch of our libraries on Github, including:
All told, we’ve released hundreds of thousands of lines of code, with new packages coming out all the time. One of the privileges of working here is that your code can have a life both within and beyond the firm.
Several of our libraries are featured in O’Reilly’s Real World OCaml, co-authored by one of our own. We’ve also funded work on several open source projects, including Mercurial, the OCaml compiler, the OPAM package manager and several development tools for OCaml. We also founded OCaml Labs, a research lab at Cambridge University devoted to improving the language.