Timm Preetz
Verified Expert in Engineering
Full-stack Developer
Timm is a full-stack developer with several years of experience building native mobile and web apps, including their back ends and infrastructure. He's worked as a team lead in various projects, where he led by example, coached, and facilitated excellent contributions from everyone. Technical-wise, Timm is exceptionally strong in Flutter/Dart, Go, and TypeScript/React.
Portfolio
Experience
Availability
Preferred Environment
MacOS, Visual Studio Code (VS Code), Flutter, Go, Dart
The most amazing...
...project I've led was the new ABOUT YOU eCommerce app (7 million MAUs) and back end, which we released after just nine months. Customers love it: 4.8/5 stars.
Work Experience
Lead App Developer
ABOUT YOU
- Rewrote the existing ABOUT YOU app (7 million MAUs) from scratch in Flutter; we released it to the App Store release within nine months after the 1st commit.
- Created a back end specifically for the app written in Go/gRPC, which served our needs for backward compatibility much better than the previous PHP/REST one.
- Oversaw the step-by-step country-wise rollout and continuous A/B tests for new feature updates.
- Onboarded various developers onto the new stack after the initial development, doubling the team size to increase resilience and accelerate speed.
- Rolled out the back end (initially written exclusively for the app) to serve also the web-based shop front ends, thus simplifying the client's overall back-end infrastructure.
- Set up CI pipelines for both the app and the back end, testing every commit and deploying them to a testing environment. It also released the app to the stores or deployed the back end to production in just one more click.
- Introduced application monitoring with New Relic and Amazon CloudWatch, with escalating alerts for any anomalies.
- Wrote a custom scaling script (based on the monitored metrics) that scaled much faster and was more aligned with the spikes in demand than the AWS standard tools.
Flutter Developer
Mawdoo3 Ltd
- Developed an MVP chatbot app ready for release in the App Store.
- Wrote a Go-based back end for user and chat history management.
- Set up CI/CD pipelines to continuously push tested builds to stakeholders.
Game Developer (Transpiration)
Goodgame Studios
- Extended an automated code transpiler which converted the existing ActionScript code from the Flash game to TypeScript which then rendered the game on HTML Canvas, so it became accessible to users who didn't have Flash installed.
- Increased the readability and "humanness" of the generated code to prepare it for the eventual switch when developers would stop writing ActionScript and start using the migrated TypeScript code as the main source.
- Improved the performance of the Flash compatibility-layer to account for different performance characteristics between Flash and the browser.
- Rolled out this new technology for the company's most popular game.
Team Lead of UI Components
Learnship
- Rewrote the client's existing online classroom client—which facilitated video-calls and interactive whiteboard sessions—from a legacy jQuery-codebase to React/TypeScript. This was rolled out to all customers worldwide within three months.
- Designed a new event-sourced, microservice architecture for the client's back end to replace a PHP monolith.
- Adapted the now rewritten clients so that they could speak with the new as well as the old back end.
- Added WebRTC support to the classroom so that customers could easily join with a recent browser or mobile device. This allowed the whole company to expand its teachings to customers on the go.
- Instituted code reviews and continuous integration practice.
Experience
ABOUT YOU App
https://apps.apple.com/de/app/about-you-mode-online-shop/id985244644Skills
Languages
Go, Dart, TypeScript, Swift, C#, ActionScript 3
Frameworks
Flutter, gRPC
Paradigms
Microservices, Mobile Development, Cross-platform
Platforms
Mobile, MacOS, Docker, New Relic, Amazon Web Services (AWS), Visual Studio Code (VS Code), Android, iOS
Other
Full-stack, Software Architecture, Technical Leadership, Web Scraping, Architecture, Team Leadership, CI/CD Pipelines, Autoscaling, Mobile Applications, Live Chat
Libraries/APIs
React, Node.js, WebRTC
Tools
AWS Fargate, Canvas, Flash, Bamboo, GitLab, GitLab CI/CD, Amazon CloudWatch
Storage
MySQL, PostgreSQL
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