01 — Introduction
Engineering scalable
systems that ship.
I'm Selwyn — a Java and Spring Boot engineer building full-stack products end to end, from backend APIs and microservices to React and Next.js on the client. Focused on Investment Management, Digital Assets, and emerging technologies in finance.
Read the Blog
02 — Latest writing
Recent Writing
Inside Laya: The Architecture of a Decision Model, Rebuilt From Its Code
Decision models answer in one forward pass, with a probability for every option you hand them, and never write a word. Nobody has published a paper on how one is built. Laya's code is open, so here is the whole machine drawn out, layer by layer, in the style of the transformer diagram you already know.
Jev in the Break Queue: Your Break Queue Doesn't Need a Model That Talks
TypeSafe's Jev returns a typed decision with a probability instead of prose, in milliseconds and for a fraction of a cent. Applied to NAV reconciliation break triage, with a live simulator showing where to set the confidence gate and why calibration decides whether that gate means anything.
The Keyed Worker Pool: Parallel Kafka Consumers That Keep Order
Kafka orders records inside a partition. The moment you hand a batch to an executor, that guarantee is gone. Four interactive simulations of the machinery that gets parallelism back without losing order: mailbox dispatch, the low-watermark commit, pause-based backpressure, and the rebalance gap no broker setting can close.
03 — Topics
Browse by Category
04 — Expertise
Building production-grade
financial technology.
Specializing in investment management platforms, digital asset infrastructure, and high-performance backend systems. Working solo means direct engineering — no relay.
Backend Architecture
Java, Spring Boot, microservices, API design, and high-throughput data pipelines.
Full-Stack Development
React, Next.js, TypeScript — from database design to responsive frontend UI.
FinTech & Digital Assets
Tokenized securities, fund accounting, SEC compliance, and blockchain integration.
05 — Connect
Let's build something
together.
Whether it's discussing technology trends, collaborating on projects, or sharing feedback — I'd love to connect.