Project Portfolio

Highlights of my projects from the recent and further past. Most of these were teamwork projects where I took leadership or significant part that required in-depth understanding of the technologies mentioned below.

ToolTime Team Augmentation

December 2022 • Client: ToolTime GmbH, Berlin

ToolTime is a job management software for tradesmen, a startup founded by Wisag a large German service group.

I helped out the team to build features in their consumer facing web product using TypeScript and React while they were having a temporary hiring shortage.

Shepherd.com

December 2020 to present • Client: Ben Fox, Shepherd.com

I have built Shepherd.com from grounds up with close collaboration of the founder and a visual designer. Shepherd aims to revolutionize how we discover new books.

Technologies used:

• Python and Django to build the public website and the content management system (using Django admin)
• Bootstrap.css and vanilla JavaScript on the front-end
• Heroku for hosting, PostgreSQL for data storage, Cloudinary for processing images and Cloudflare for CDN
• GitHub Issues for collaboration and GitHub Actions continuous delivery

I have also written about building Shepherd in detail.

Mileways Flight Tracker

April 2021 to present • Client: Codeventures GmbH, Münich, Germany

Mileways is a flight tracker for air travellers, available on iOS. I took over the responsibilities for developing and maintaining the back-end in 2021.

Technologies used:

• Java and Spring Boot to build a REST API serving the mobile app
• FlightStats API for sourcing flight data
• MySQL for data storage
• DigitalOcean for infrastructure (managed Kubernetes and database servers)

Moving SoundCloud Sonar to Google Identity-Aware Proxy (IAP)

March 2021 • Client: SoundCloud

This short project involved moving Sonar, SoundCloud’s internal tool to use the IAP proxy to authenticate and authorize employees using Google single sign-on.

Journeyman Recruiting Platform

June 2019 to 2021 • Client: Journeyman

I am doing regular maintenance and feature development on this platform specialized in recruiting German craftsmen for English speaking countries.

Technologies used:

• React and Redux to build a responsive app for both desktop and mobile
• Serverless Framework to implement API endpoints and event handlers as Lambdas
• DynamoDB and Elasticsearch for data storage and retrieval
• Continuous delivery with AWS CodeBuild and CodePipeline
• AWS ApiGateway, SNS, IAM, CloudWatch

SoundCloud 3D Secure Payments

August 2019 • Client: SoundCloud

Helped SoundCloud’s Payments Team to implement 3D Secure payment authentication protocol in order to achieve PDS2 regulation compliance. The project heavily relied on pair programming.

Technologies used:

• Adyen for processing credit card payments
• Ruby on Rails and MySQL on the back-end
• React and Redux with TypeScript at the user interface

Kiro Project Management Analytics

2019 to 2021 • Client: Kiro

I took over this project after a prototype phase and continued the development to shipping a minimum viable product (MVP).

Besides software development I helped the founder in shaping the product strategy, project management, hiring and collaboration with the UX designer.

Technologies used:

• React, MobX and Rebass with Styled System to build a responsive app for both desktop and mobile
• Stripe payments integration
• Python with Flask on the back-end and a MongoDB database
• Infrastructure on AWS managed with Ansible
• Continuous delivery with CircleCI

Rebuilding SoundCloud OAuth Connect

March 2019 • Client: SoundCloud

As part of SoundCloud’s modernization efforts I rebuilt the OAuth Connect user interface using a modern web stack.

Technologies used:

• React and Redux with TypeScript to implement the user interface
• Jest for extensive unit testing
• Webpack and Node.js for development tooling

MusiCurve

Oct 2017 to 2019 • Client: why do birds

MusiCurve is a simple to use tool that allows arranging precomposed and reusable brand music to a video and exporting a final video file. MusiCurve won the UX Design Award in 2022 in category “Product”.

My responsibilities not only included building the software from grounds up but also introducing why do birds to software development and the project management of software projects.

Technologies used:

• Vue.js and Vuex for UI prototyping and final implementation of a heavily interactive user interface
• Web Audio API for processing audio signals (wrapped by Tone.js)
• Webpack and Node.js for development tooling

Microservice Project for the Automotive Industry

June 2018 to Sept 2018 • Client: Elasticbrains and Deloitte Deutschland *

* The main client is a Fortune Global 500 company but can not be named here due to NDA.

A microservice for the Java EE platform consuming data from Kafka, turning it into a time series database exposed via a REST API over HTTP.

As a software architect on a small team my role included a wide range of responsibilities from making sure the development follows the detailed specification and internal corporate software standards to building features and making sure they are shipped to the client’s infrastructure.

Technologies used:

• Java 8 EE application running on Payara Server
• JAX-RS and Swagger for implementing REST endpoints
• Kafka for consuming incoming data
• Cassandra NoSQL database for big data persistence
• Multi-project multi-module Maven setup for dependency management
• OpenShift and Jenkins for continuous delivery

SoundCloud Partner Tools

2012 to 2017 • Employer: SoundCloud

A series of ongoing projects of business-to-business services to SoundCloud’s key partners ranging from large international record labels to small independent ones. The implementation involved building well scoped (micro)services.

• Scala, Java and (j)Ruby for business logic and internal APIs
• Finagle Framework for concurrent RPC
• MySQL, Cassandra and Hadoop for storing and processing data
• Messaging with RabbitMQ and Kafka
• Continuous delivery of Docker containerized applications to Kubernetes
• Team owned most of the DevOps duties

SoundCloud Stats

2014 • Employer: SoundCloud

Complete rewrite of the performance analytics pages SoundCloud provides to the music creators on the platform.

• D3.js for data visualization
• Backbone.js for user interface
• Node.js and Webpack front-end developer tooling
• Go and Scala for the supporting microservices

SoundCleod

2013 to 2021 • Open source project

Started as an afternoon hack now used by thousands daily SoundCleod is a desktop application which brings SoundCloud to macOS and Windows without using a web browser.

• Built using Electron to wrap SoundCloud’s web application
• Freely downloadable open source software with external contributors on GitHub
• Deployed using a (mostly) automated automatic update process

Gawker Web Performance Optimization

2012 • Employer: Gawker Media

Lead the optimization project which eliminated front-end bottlenecks and reduced page load time from 5 to 3 seconds (50%) on all websites of the Gawker Media blog network (Gawker, Lifehacker, Kotaku, Gizmodo).

• JavaScript and jQuery
• Various web performance analysis tools for finding bottlenecks
• Introduced Backbone and RequireJS for a better front-end architecture
• Scala on the back-end

iWiW.hu Social Network

2005 to 2011 • Employer: Virgo Systems

iWiW was the number one social network in Hungary before Facebook. I participated in various sub-projects during the years worked at Virgo Systems.

• Java (J2EE) with Maven on the back-end
• Implemented API’s for third parties with OpenSocial and OAuth
• Built a JavaScript framework in-house on top of jQuery