Jane Street Tech Blog

Using OxCaml to implement type-safe reference counting between OCaml and Python

9 days ago

Jane Street is known for being an OCaml shop, but for years...

Formal methods and the future of programming

17 days ago

I’ve been telling people for the last 25 years that Jane Street...

strace-ui, Bonsai_term, and the TUI renaissance

29 days ago

We’ve always found strace useful but somewhat hard to work with. Its...

Using group theory to explore the space of positional encodings for attention

2 months ago

Attention is a computational primitive at the core of modern language models...

Can you reverse engineer our neural network?

4 months ago

A lot of “capture-the-flag” style ML puzzles give you a black box...

Results from the Advent of FPGA Challenge

4 months ago

At the end of last year, we decided to try something new...

I design with Claude more than Figma now

5 months ago

For a long time I was skeptical of LLMs—whenever I reached for...

Fun with Algebraic Effects - from Toy Examples to Hardcaml Simulations

6 months ago

I recently ported the Hardcaml_step_testbench library, one of the libraries that we...

Getting from tested to battle-tested

7 months ago

Advent of FPGA — A Jane Street Challenge

7 months ago

Advent of Code has long been a favorite December ritual at Jane...

What the interns have wrought, 2025 edition

10 months ago

Yet again, we’re at the end of our internship season, and so...

A Higgs-bugson in the Linux Kernel

12 months ago

We recently ran across a strange higgs-bugson that manifested itself in a...