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 our systems every day – but the group behind them isn’t. We have fewer than a hundred developers, which means that each person has a chance to make a substantial impact.
We organize our work into project-oriented teams, each with the independence and responsibility to make real decisions that impact the future of the firm. That, combined with our size, 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: We use OCaml, a statically typed functional language, as our primary development platform.
Jane Street’s development 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 just about productivity: programming in a rich and expressive language like OCaml is just more fun.
The same concerns go beyond language choice. We’re happy to spend time and money on making it easier 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 believe open source should be a two-way street, which is why we’ve released some of our most significant projects, like:
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.