Freelance full-stack engineer · Fukuoka, Japan

I build and modernize systems that need to move data — and people — reliably.

Ten years shipping production Rails applications, migrating infrastructure between clouds, and building the real-time systems that keep teams and platforms in sync. Available for freelance and contract engagements, in Japan and remote.

Based in Fukuoka, Japan
Experience 10+ years, full-stack & infra
Languages German · English · Japanese (N1)
Engagement Freelance / contract

Services

Focused engagements, from a single migration to end-to-end product delivery.

01

Rails application development

New applications built end to end — requirements, architecture, REST APIs, and front-end delivery in Rails, Angular, or Vue.

02

Cloud & database migration

Moving platforms between clouds (Azure ↔ AWS) and databases (MS SQL Server ↔ PostgreSQL) without breaking what's running.

03

Framework upgrades & test modernization

Upgrading Rails major versions, resolving dependency conflicts, and migrating test suites (MiniTest → RSpec) to a maintainable baseline.

04

Real-time & infrastructure-as-code

WebSocket and real-time system design, plus AWS infrastructure provisioned and version-controlled with Terraform.

Recent work

A selection of freelance engagements from the past few years.

2025 – 2026
GA Technologies Inc, Tokyo

Test suite & framework modernization

  • Migrated the unit-test suite from MiniTest to RSpec, standardizing test-driven development practices across the codebase
  • Upgraded the platform to the latest major version of Ruby on Rails, resolving breaking changes and dependency conflicts
  • Built integration tests to safeguard against regressions on the upgraded framework
RailsRSpecTDD
2023 – 2024
Davey Japan Inc, Fukuoka

Vehicle-sales platform & cloud migration

  • Designed, developed, deployed, and operated a new vehicle-sales application replacing a legacy system
  • Migrated data from Azure to AWS using AWS DMS and converted the database from MS SQL Server to PostgreSQL
  • Built REST APIs in Rails and customer- and staff-facing front-ends in Angular; deployed to AWS EC2
RailsAngularAWS DMSPostgreSQL
2021 – 2023
Kotozna Inc, Fukuoka

Real-time interpreter application

  • Delivered several components of a real-time interpreter application for the tourism industry
  • Analyzed and provisioned cloud infrastructure as code using Terraform on AWS
  • Developed a WebSocket library in Flutter (Dart) enabling real-time communication in the mobile app
TerraformFlutterWebSocketFlask

Stack

Tools I reach for most often — happy to work outside this list.

Languages
RubyJavaScriptJavaKotlinDartGoPython
Frameworks
RailsFlutterVueAngularSpring BootFlask
Infrastructure
AWSDockerKubernetesTerraformPostgreSQL

About

I'm a full-stack engineer based in Fukuoka, Japan, with a Diploma in Computer Science from the University of the Federal Armed Forces of Germany. My career started in systems administration and IT security before moving fully into software development in 2015 — that background shows up in how I approach infrastructure and migrations today: carefully, and with an eye for what can go wrong.

Since 2021 I've worked as a freelancer with companies across Japan, building production applications and leading cloud migrations end to end. I'm comfortable working directly with Japanese and international clients, and I bring the same rigor to a small freelance engagement as I would to a long-term platform.

  • GermanNative
  • EnglishFluent
  • JapaneseJLPT N1