Hey, I'm
Jun Kai

San Francisco & Singapore

Most of what I build starts where something else stopped: a benchmark someone set, or a problem taken as solved until you measure it. Curiosity mostly, with a competitive streak. Professionally that's full-stack product engineering, with deeper specialisation in Rust numerical computing, security tooling and uncertainty quantification.

• pyvolr

  ~2× faster than the next-fastest library at 1M implied-vol solves — and the only one still exact at option prices of 1e-215, where the others return wrong constants without erroring.

• secrets-spotter

  Finds leaked credentials in files, pages and live network traffic. 60+ patterns, one Rust core, a CLI and a browser extension, plus a disclosure policy nobody asked me for.

• Oceanfront Hardware

  A B2B checkout-first storefront, live since 2023 and still a one-person system. One search rebuild took query latency from 700ms to 20ms.

• AI4X 2025

  Quantifying uncertainty in physics-informed neural networks — knowing when the model does not know.