Portrait of Timm Preetz Timm Preetz Freelance software architect and full-stack developer

CV

A concise timeline of recent work across apps, backend systems, framework engineering, and developer tooling.

timm.preetz.xyz/cv

2025-10 - 2025-12

greatRPC

Application Developer · Freelance

Munich

Built a modern gRPC / Protobuf client for Apple platforms.

  • Built a modern gRPC / Protobuf client for macOS and iPadOS using SwiftUI and Rust.
  • Rust
  • SwiftUI
  • gRPC

2025-01 - 2025-07

Serverpod AB

Senior Backend-Framework Engineer · Freelance

Remote

Worked on framework internals, migrations, and authentication.

  • Improved the database migration engine to handle more edge cases.
  • Added support for Dart record and container types in the client-server protocol and data storage.
  • Created the next generation authentication module, including passkeys, JWT, magic links, and backwards-compatible legacy account support.
  • Dart
  • PostgreSQL
  • Google Cloud

2023-11 - 2024-11

TELESON

Senior Mobile App Developer

Munich, Germany

Rebuilt the product as a cross-platform Flutter application with offline-first workflows.

  • Built a new Flutter mobile app replacing separate Android and iOS code bases while porting business logic from Swift and Kotlin.
  • Added robust offline support with local databases and sync workflows that recover gracefully after reconnect.
  • Set up testing infrastructure and introduced CI workflows with CodeMagic.
  • Sped up client development by auto-generating APIs from the spec.
  • Implemented on-device PDF editing workflows for filling and signing forms.
  • Flutter
  • Offline-first
  • PDF editing
  • OpenAPI

2023-07 - 2023-09

Mawdoo3

Senior Full-Stack Developer

Remote

Built an MVP chat product around the client’s Arabic LLM.

  • Built the MVP chat app around the client’s custom Arabic GPT-style model.
  • Wrote the backend for user management, chat history, and integration with Python-based AI services over gRPC.
  • Set up CI/CD with GitHub-driven deployments to Google Cloud Run.
  • Flutter
  • Go
  • gRPC
  • Python
  • PostgreSQL
  • Google Cloud

2021-07 - 2023-06

MySports GmbH / Magicline GmbH

Senior Mobile App Developer

Remote

Scaled a shared Flutter foundation across several white-label products.

  • Supported the release of three new end-user white-label mobile apps.
  • Rewrote the white-label apps to share most code between them.
  • Led the technical implementation of a new UX and design system.
  • Mentored the client team in development best practices.
  • Introduced automated tests and built toward a CI/CD flow with growing coverage.
  • Led development of the new Magicline app for studio personnel from scratch.
  • Flutter
  • OpenAPI
  • Mentoring

2018-05 - 2021-07

ABOUT YOU

Head of Architecture (Shop Applications)

Hamburg, Germany

Helped lead the app architecture transition into Flutter and service-based systems.

  • Saw the new Flutter app through to release as team lead.
  • Migrated code from legacy backends to newer services.
  • Prototyped and kickstarted several new initiatives across backend systems and customizable shop applications.
  • Contributed public speaking and architectural leadership across teams.
  • Flutter
  • Go
  • AWS