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Hello! I’m Jake, a Lead Developer at a UK financial services consultancy.
I move comfortably between .NET backend architectures with Clean Architecture and DDD, and frontend work with React and Next.js.

About me

My name is Jake Ryu. I was born and raised in South Korea, where I began my journey as a software developer. With over 20 years of experience as a software developer, I have honed my skills and expertise across various technologies and projects. I later moved to the UK to help build the local systems for Hyundai Motor Company. I have since settled here and am currently working as a Lead Developer at Barnett Waddingham (part of Howden), a UK professional services consultancy specialising in risk, pensions, investment, and insurance.

I value clean code, rigorous testing, and pragmatic modernisation — replacing slower manual processes with faster, more reliable software, and shipping it in a way the business can actually trust. Using Clean Architecture and Domain-Driven Design (DDD), I manage dependencies cleanly and verify business logic through clear domain models. What I aim to leave behind is not just shipped features, but patterns, standards, and infrastructure that other teams can build on.

When I'm not coding, I enjoy long walks with audiobooks — usually on investment, self-development, or fiction — and spend weekends working on personal projects with my mix of AI coding assistants. I also love travelling with my family and capturing those moments through my cameras.

My Latest projects

Feature Toggle Platform

Sole developer. Rolled out feature toggles across the entire pension administration solution, enabling safe and targeted releases.

.NET Framework 4.7.2 – .NET 8
Azure App Configuration
Feature Flags

Team Retrospective Board

A custom retro board I built solo when our Trello hit licence limits. AI-assisted development with Claude Code, applied responsibly.

Next.js
Cosmos DB
React
Claude Code

Pension self-service

A website for pension members to choose their preferred name and access all pension information. I provided the API and rebranded old webpages.

ASP.NET Web API
React
Azure
Terraform

Adserve Studio

A collection of SPAs offers comprehensive audio planning, trafficking, and revenue optimization. I worked as a full-stack developer.

ASP.NET Web API
React
AWS
PostgreSQL

Moneybox App

Moneybox is a mobile app that simplifies saving and investing. As a platform developer, I created modules for batch processing calculations.

ASP.NET Web API
Native App
Azure
SQL Server

Pledge Service Integration

Backend lead. Integrated a third-party 'plant a tree' pledge triggered when members opt out of paper communications. Azure Functions with persistent retry.

Azure Functions
ASP.NET Core

My skills

C#
.NET Core
.NET 9 HybridCache
RESTful API
DDD
TDD
BDD / SpecFlow
Clean Architecture
CQRS
MediatR
MassTransit
RabbitMQ
OpenAPI Spec
JsonPatch
Entity Framework
Dapper
linq2db
Fluent Validation
Fluent Migrator
SQL Server
PostgreSQL
RavenDB
DynamoDB
Azure Function
Azure Service Bus
Azure Data Factory
Azure Key Vault
Azure DevOps
GitHub Actions
Octopus Deploy
Feature Flag
Jira
AWS
Terraform
Docker
Git
CI/CD
xUnit
Moq
Serilog & Seq

HTML
CSS
SASS
JavaScript
TypeScript
React
Context API
Reducer
Next.js
Node.js
Tailwind
Bootstrap
MongoDB
Jest
Testing Library
Cypress

AI Tools

Used responsibly with rigorous human verification

Claude Code
OpenAI Codex
Google Gemini
NotebookLM
GitHub Copilot

Areas of interest

Kubernetes
Production microservices operations

My experience

My career has been a sequence of deliberate steps — each role chosen to deepen something the previous one couldn't fully give me. From early full-stack roots in Seoul, to global-scale enterprise systems at Hyundai, to test-driven microservices at ByBox, to regulated cloud fintech at Moneybox, to React-first product engineering at Adserve, to modernising legacy systems at Barnett Waddingham — every move added a layer I now carry into the next.

The apprentice chapter

Web Developer

Seoul, South Korea

Started out working broadly across web development, databases, and Windows servers — gaining breadth before depth. The most memorable delivery was an ERP project for Lotte Duty Free Shop, Korea's largest duty-free retailer, built with ASP.NET, IIS, MS SQL Server, and ActiveX.

What I took forward: breadth across web, databases, and servers — and the confidence that comes from shipping production systems for real clients from day one.

2000

The foundation chapter

Application Architect

Hyundai Motor UK

Eleven years of full-cycle architecture across the UK dealer network, marketing, sales, finance, and import operations — many projects replacing paper-based processes with digital ones. Local stack was .NET; global projects integrated SAP ERP and Oracle CRM. Notable deliveries included a vehicle registration system in collaboration with the DVLA and a mobile inventory app for the import centre, for which I introduced the team's first RESTful API.

What I took forward: a deep instinct for translating business problems into technical solutions, and an early conviction that good software is measured by how it changes the work, not how clever the code is.

2006

The discipline chapter

Software Developer

ByBox (Homebased, UK)

My first role in a microservice-based environment. ByBox runs a nationwide network of electronic lockers where delivery drivers deposit and collect items via mobile. I worked full-stack across distributed services — backend in ASP.NET Web API with NServiceBus for inter-service messaging, and a React + Redux operations dashboard. The team's strict TDD discipline and SpecFlow specifications, written with business analysts before any code, drove every behavioural test end-to-end.

What I took forward: testing as a mindset, not a phase — and the SpecFlow/BDD habit of writing behaviour with business analysts before writing code.

2017

The cloud and scale chapter

Senior Engineer

Moneybox (London, UK)

At Moneybox I built the backend of a regulated UK savings and investment platform on Azure, where every line of code touched customer money. I led batch interest calculation engines for 95-Day Notice Accounts and Cash Lifetime ISAs, handling edge cases like early withdrawals and ISA allowance boundaries. Built on Azure Event Hub and Azure SQL with detailed error logging and recoverable failure handling, deployed through TeamCity and Octopus.

What I took forward: large-volume batch processing, detailed error logging, recoverable failure handling, and a healthy respect for regulated environments where silent failures aren't an option.

2018

The product engineering chapter

Senior Software Engineer

Adserve (Homebased, UK)

Full-stack delivery for Adserve Studio, a global supply-side advertising platform. The team's deliberate policy of avoiding third-party component libraries was an unusual constraint — every React component (sortable/filterable data grids, foldable accordions, heatmap grids) had to be built from scratch with hooks, context, and reducers. Backend on ASP.NET Core with Clean Architecture and CQRS, deployed on AWS via Jenkins.

What I took forward: deep practical experience in component design, state management with Context API and reducers, and an appreciation for the trade-offs in choosing build-vs-buy at the component level.

2020

The leadership and modernisation chapter

Lead Developer

Barnett Waddingham (Amersham, UK)

On the Hyperion team I lead the modernisation of legacy pension administration systems on .NET, React, and Azure — raising engineering standards, driving cloud-native adoption, and delivering business-impacting features end-to-end. I authored the REST API standards now adopted company-wide, drove the move to event-driven architecture via Azure Service Bus, and led adoption of App Configuration, Function Apps, Key Vault, and Feature Flags. Beyond technical work, I mentor the team on modern React patterns and Cypress testing.

What this chapter is teaching me: the patience and precision needed to modernise legacy systems without breaking them — and how to build infrastructure (REST API standards, Feature Toggle Platform, CI/CD pipelines) that other teams across the company can build on.

2021

Publications

Pro ASP.NET MVC 5 (Korean translation)
2014 — First Korean-language ASP.NET MVC 5 book, with the ASP.NET User Group in South Korea.
ASP.NET REBOOT — ASP.NET Core series
2015 — Articles introducing ASP.NET Core to a leading South Korean software magazine.

Certifications

Award in Pension Essentials
2024 — UK pensions industry foundational certification.
Microsoft Azure Developer Associate
2022 — Microsoft Azure cloud development certification.
AWS Cloud Practitioner
2021 — Amazon Web Services foundational cloud certification.

Thanks for reading — let's connect.

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Hello! I’m Jake, a Lead Developer at a UK financial services consultancy. I move comfortably between .NET backend architectures with Clean Architecture and DDD, and frontend work with React and Next.js.