Solving,

not selling

The work at Jane Street is technologically intense, with software playing an essential role in everything we do. We consider ourselves as much a technology company as a trading firm.

Complex Challenges

Our trading crosses multiple exchanges, regulatory regimes, asset classes and time zones, and demands that we analyze and respond to vast amounts of data from diverse sources in real time. Meeting this challenge requires a serious investment in software and technology.

In-house Solutions and Expertise

Software is an integral part of how we approach problems, whether we’re designing a trading strategy, managing the operational complexities of a new trade-flow, or building statistical models. And because we have a unique niche in the market, much of that software needs to be created in-house, by people who have developed a deep understanding of what we do.

Coding Everywhere

Writing code isn’t restricted to the technology groups. The trading desks have built their own software for years. Over time, that software has gotten increasingly sophisticated, both in what is accomplished and the tools used. Today, every new trading hire goes through a month-long bootcamp that teaches them the basics of programming in OCaml, our language of choice.

The OCaml difference

We’ve made the unusual choice of using OCaml, a statically typed functional programming language, as our primary development language. Languages in this family, like Haskell, SML, F# and Scala, are typically viewed as powerful but impractical, in part because they’re thought to be too difficult for the average programmer, and in part because nobody else seems to use them.


We’ve taken a different view. We believe that functional programming boosts our productivity, and we don’t mind going our own way. When you're solving hard problems, there’s no substitute for using the best tools available.

OCaml in particular provides a great combination of qualities. It’s streamlined and efficient, making it possible to achieve performance near that of C. At the same time, its powerful type system acts as a rich and well-integrated set of static analysis tools that help you improve the quality of your code, catching bugs at the earliest possible stage. Billions of dollars of transactions flow through our systems every day, so that means a lot to us.


OCaml is also highly expressive, letting you convey your ideas clearly, precisely and readably. We believe that if you want to build high quality, robust software, readability is essential.

Jane Street is deeply invested in OCaml and the larger OCaml community. Here are some ways we're trying to help it grow:

Creating rich open-source libraries (all available on github), including Core, an alternative to the OCaml standard library, and Async, a sophisticated library for concurrent programming. Core and Async will be featured prominently in Real World OCaml, a book coming out this year from O'Reilly.

Spreading the word People at Jane Street have given talks about OCaml at a bunch of universities, including Harvard, Penn, Princeton, Brown, Cornell and CMU, as well as programming language conferences like ICFP and POPL. We've also run tutorials for New York City's own Hacker School and the CUFP workshop.

Founding OCaml Labs a research laboratory at Cambridge University dedicated to improving OCaml and the surrounding toolchain.

Funding improvements to OCaml Jane Street has funded several significant performance and usability improvements to OCaml, as well as the creation of the excellent OPAM package manager, developed by OCamlPro.

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