Last updated: October 2026

I'm Johnny Kao.

This GitHub is a second Johnny: it is the more experimental, technical, and personal side of me — selected code, open-source contributions, passing curiosities, and ideas I feel like keeping around.

I spend most of my time around finance, strategy, cross-border questions, data, research, and digital systems, but I have never liked staying in just one lane.

Recently, I have been spending more time on upstream open-source engineering, especially around performance, correctness, concurrency, and low-level infrastructure.

A recurring pattern in the work is simple: find an expensive or unsafe path, establish the behavioral boundary, reduce it to the smallest defensible change, benchmark or differential-test it, and upstream it.

• c-blosc2 #805 — avoided unnecessary parallel startup and worker wakeups for low-parallelism jobs; a targeted 64-byte workload improved from 35.86 μs → 2.02 μs.
• Memray #1035 — improved Linux/glibc Tracker contention handling, reducing runtime by up to 28% at 256 threads in an allocation-heavy workload.
• urllib3 #5287 — optimized the common single-value header path, improving representative request-construction workloads by roughly 9–13%.
• python-blosc2 #728 — removed redundant full-block zeroing in the NumPy miniexpr gather path, improving tested workloads by roughly 2–15%.

Additional merged correctness work spans NumPy, SciPy, and free-threaded Python support in python-blosc2.

• 2026 — 📊 Deepened upstream OSS work across scientific Python, systems, networking, profiling, and compression
• 2025 — 🚀 Moved from consulting into startup finance and corporate development, supporting a multi-billion-JPY fundraising extension and board-level decisions
• 2024 — 🧭 Worked across digital transformation, AI adoption, future banking strategy, and RWA tokenization
• 2022–2023 — 🌐 Worked on institutional digital assets, wealth management, payments, and emerging financial infrastructure
• 2020 — 🧊 Code preserved in GitHub’s Arctic Code Vault
• 2019 — 🏦 Worked on virtual banking and cross-border financial infrastructure
• 2015–2018 — 💳 Built and worked around payments, Bitcoin-linked card infrastructure, fintech, SaaS, and digital-asset systems
• 2013 — 🤝 Volunteered in Tunisia

Some repositories here are serious engineering work. Some are experiments. Some exist because I wanted to understand one obscure problem properly.

That distinction is intentional.