Timm Preetz

from https://timm.preetz.xyz

greatRPC

2025-10 – 2025-12

Application Developer

Built a modern gRPC/protobuf client (think "Postman") for macOS and iPadOS using SwiftUI and Rust.

2025-01 – 2025-07

Senior Backend-Framework Engineer

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: Overhauling the social login; adding JWT, passkey, and magic link support; supporting legacy accounts in a backwards compatible way

2023-11 – 2024-11

Senior Mobile App Developer

Built new Flutter mobile app version replacing 2 separate Android and iOS code bases (porting business logic from Swift & Kotlin)
Added full offline support using local databases (Hive, Floor) and implementing a robust sync framework to update the server once the client regains network access
Set up testing infrastructure and introduced CI workflows (CodeMagic)
Sped up client development by auto-generating APIs from the spec
Implemented on-device PDF editing workflows (filling & signing forms)

2023-07 – 2023-09

Senior Full-Stack Developer

Built the MVP chat-bot app for the client’s custom Arabic GPT-style LLM
Wrote the backend for the app (user management, chat history, interfacing with the ML API services), communicating with the downstream app and upstream Phyton-based AI backends via gRPC
Set up CI/CD with deployments to Google CloudRun from GitHub

2021-07 – 2023-06

Senior Mobile App Developer

Supported the release of 3 new end-user white-label mobile apps
Rewrote the white-label apps to share most code between them
Technical implementation of a new UX / design system
Taught the client’s existing team in development best practices
Introduced automated tests to the codebase and steadily increasing coverage, ending up with a CI/CD flow
Lead the development of the new Magicline app for studio personnel from scratch

2018-05 – 2021-07

Head of Architecture (Shop Applications)