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CV & Engagements

Senior Software Engineer & Technical Consultant

Software developer with over 25 years of experience, formally trained since 1996. Backend work with Ruby on Rails, Go and Elixir these days; many years of .NET in between. Most recently nearly a decade at NEW WORK SE (XING, kununu): Senior Engineer on the AdManager team, then Team Lead Engineering at XING Marketing Solutions, then Senior Engineer in the Platform cluster.

Available for consulting, interim engineering, tech lead work and permanent roles. Most useful in the messy situations: legacy systems, migrations, integrations, performance and scaling problems, projects that need a lot of coordination. When I come in, I'm in the code with the team.

Where I add value

Legacy and critical systems

I find my way around old codebases quickly. When something is broken, I can usually tell whether the problem lives in the code, the architecture, the deployment, or in who's supposed to own it.

Migrations and bottlenecks

Stuck migrations, platform rebuilds, performance work, integrations, projects that need both technical depth and a lot of coordination. I sit with the team and write code.

Engineering with business in mind

I think about what the code costs the business as much as how it's written. A team that ships features without that lens often ships the wrong ones.

Stretched teams

When a team is short-handed or burning out, I step in. Run 1:1s, prepare decisions, give management a realistic picture. The code still gets written.

Focus areas

Experience

Indie Developer & Freelance
from 02/2026
Own products and consulting work following nearly a decade at NEW WORK SE.
  • DopaLoop: iOS app for people with ADHD. Concept, development and App Store release. SwiftUI, CoreML.
  • TheLawin.dev: micro-SaaS that turns a JSON object into an EU-compliant invoice PDF (ZUGFeRD, XRechnung, Factur-X). Go backend, custom documentation site.
  • Quilence: iOS app in the sleep and deep-work space, currently in development.
  • Open source: git-issues, Backfeedr, uptimer and other tools for indie iOS development, agent workflows, crash reporting and homelab monitoring.

Swift SwiftUI Go Ruby Claude Code spec-kit Docker ProxmoxVE

NEW WORK SE (XING, kununu) · Hamburg
10/2016 – 01/2026
Jobs network and recruiting platform · approximately 1,400 employees
Senior Engineer, Platform Cluster
04/2020 – 01/2026
  • Ownership of one of the group's highest-traffic Accounts apps; currently leading the migration from Elixir to Rails.
  • Designed and implemented account synchronisation between XING and Onlyfy, plus between Prescreen and Onlyfy; both in production.
  • Contributed to the company-wide migration from Atlassian HipChat to Slack.
  • XING Locator: in-house mapping service for office locations, later extended with tracing and prevention features during the COVID-19 pandemic.
  • Introduced distributed tracing (Jaeger, Dapper pattern) into the Ruby community of practice; spoke about it at RubyConf Bangkok.
Team Lead Engineering, XING Marketing Solutions GmbH
04/2018 – 03/2020
  • Line and technical management of up to 12 employees and freelancers.
  • Hiring, 1:1s, performance management, skill development.
  • Guided the team through the wind-down of Marketing Solutions GmbH and its integration into the platform organisation.
  • Built and evolved the self-service platform on Rails and React, plus its integration with the mobile native-ad stacks.
Senior Software Engineer, AdManager
10/2016 – 03/2018
  • Took the AdManager prototype to a fully working ad-delivery platform.
  • Scala-based backend bidding with integration into the data-science stack; self-service frontend in Rails and React.
  • Built the real-time bidding pipeline and click/impression processing; scaled revenue from a few k€/day to roughly 60 k€/day.
  • Integrated ad delivery into internal native-ad stacks for mobile devices.
SinnerSchrader Deutschland GmbH · Hamburg
10/2014 – 09/2016
Digital agency · approximately 500 employees at the time
Senior Ruby Developer & Scrum Master
  • Maintenance of the Unitymedia web presence: checkout flow, customer self-service portal, live deployments, client meetings.
  • Scrum Master of the TUIfly maintenance team.
  • Unitymedia/Kabel BW brand merger in a two-engineer team: technical and visual unification of two brands.
  • Designed and implemented a Redis-backed caching layer for the customer portal; extended the checkout REST API to support a mobile-app project.
Dennso Management Consulting GmbH · Hamburg
07/2012 – 09/2014
Senior Developer (Ruby on Rails & .NET)
  • Pharma startup: B2B web application for medical practices, pharmacies and statutory health insurers on Rails. Still in production today.
  • Fleet-management ERP: Senior .NET engineer in a client team. AngularJS frontend, C#/.NET WebAPI backend, Oracle.
velvetsoft GmbH
01/2010 – 06/2012
Head of Engineering & Client Projects
  • Responsible for internal engineering and the client-project business.
  • PUMA AG: Agile coach embedded in middle management. Introduced Scrum-style processes and more transparent ways of working in cross-departmental projects.
Effective Software Deutschland KG
10/2007 – 12/2009
Managing Director
  • Founded and led the company; software for private job placement and project services.
  • A client engagement with Jobdistrict GmbH grew into a desktop ERP product covering candidate and client management, commission settlement, and AVGS placement-voucher integration with the German Federal Employment Agency.
  • Still in production today; helps place hundreds of people into formal employment each year.
Netpioneer AG (freelance), Karlsruhe · for dpa
2008 – 2011
.NET Scrum Developer on the INES project
  • Contributed to the new news-production infrastructure for the German Press Agency (dpa).
  • Focus on GUI engineering: docking and window manager, custom controls following UX specifications.
  • Involved from kick-off through to rollout in the Berlin newsroom; first proper experience of Scrum in a mature setup.
Zapf Systemhaus GmbH · Oldenburg
09/1996 – 09/2004
Software Developer · IHK-certified Apprenticeship in IT
  • Worked on inventory and ERP, accounting, care-home and home-care administration, public-sector accounting.
  • Led the team's migration from VBA/VB 5+6 to .NET; designed and built a base framework adopted across the engineering team.

Education

Community & publications

Stack

Languages
Ruby, Go, Elixir, Swift, JavaScript, TypeScript, C#, SQL · previously extensive .NET, VB.NET
Frameworks
Ruby on Rails, SwiftUI, React · previously Grails and AngularJS
Databases
PostgreSQL, MySQL, Redis, Oracle
Infrastructure
Git, Docker, Jaeger, ProxmoxVE, AWS basics
Methods
Scrum, agile ways of working, microservices, REST, mentoring, technical diagnosis
AI tooling
Claude Code, GitHub spec-kit, agentic development workflows, issues as the spec hub
Languages
German (native), English (fluent), French (school-level)

Sounds like a fit?

Available for consulting, interim engineering, tech lead and permanent roles. Full CV with contact details and references on request.

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