Felix Uellendall

Data Engineer, Open Source Enthusiast and Apache Airflow Committer

About Me

Hi, my name is Felix Uellendall. I am a young Data Engineer working in a data team for a digital agency in Berlin, Germany. I joined the Apache Software Foundation in September 2019. Since then I am also an Apache Airflow Committer.

Technical Skills

I am most skilled in:

Apache Airflow Python Unit Testing

I have experience in:

Agile Methodologies Amazon Redshift AWS Bash C# CI/CD CSS dbt Docker ETL/ELT Git great_expectations HTML Java JavaScript MySQL PostgreSQL Python Pandas REST Software Design Software Development System Testing

I am familiar with:

Apache Spark Databricks Express.js GCP Golang Julialang Kubernetes Microsoft Azure Node.js Terraform Test Driven Development


German (Native speaker) and English (Upper-intermediate)


"Airflow is a platform to programmatically author, schedule and monitor workflows." - Apache Airflow

In search for a solution for the management of data pipelines I stumbled upon the Open-Source project Apache Airflow in January 2018. I really appreciate the simplicity of use, high coverage of use cases and the community behind it. That’s why I decided to give something back so I started contributing and am now a committer of this project.

"Auto-generated Diagrams from Airflow DAGs." - Felix Uellendall

A personal project to auto-generate diagrams based on Apache Airflow DAGs. Airflow DAGs specify workflows which consists of tasks which can depend on eachother. Based of these tasks and dependencies a Diagram will be generated. A Diagram visualises the provider (often cloud-based) used in the Airflow DAGs by simply displaying its logos.

"Let's build great data.." - Felix Uellendall

A personal project for building data models with dbt. DBT empowers SQL to be more elegant and efficient when it comes down to transforming data step by step in the data analytics and engineering field.


Apache Software Foundation


Apache Airflow Committer

September 2019 - Present

"The World's Largest Open Source Foundation" - Apache Software Foundation

For Apache Airflow I am..

  • writing project and code documentation
  • writing unit tests in python
  • adding new features like Airflow hooks and operators
  • reporting bugs via Jira or GitHub Issues
  • communicating with the community via email and slack
  • writing Airflow Improvement Proposals in Confluence
  • reviewing GitHub pull requests
  • helping users to join the community
  • testing and voting releases

Digitas Pixelpark GmbH


Junior Data Engineer

January 2018 - November 2020

"Germany's most impactful customer experience agency" - Digitas Pixelpark GmbH

  • built a data management platform on AWS for our data analysts and scientists to access analytics data efficiently
  • added CI/CD to our DMP (data management platform) via GitLab CI/CD which lints, tests, builds documentation and deploys our code to a development or production environment
  • built (ETL/ELT) data pipelines with Apache Airflow
  • connected new data sources (mostly via REST APIs) to our data platform
  • transformed data via SQL or Python Pandas to be analytics-ready
  • designed workflows efficiently by making use of a lot of features of Apache Airflow
  • monitored of our data pipelines

NETRONIC Software GmbH


Student Research Assistant

August 2012 - August 2016

"Our mission is to enable every SMB organization to achieve operational agility with visual scheduling." - NETRONIC Software GmbH

  • built a .NET Windows Forms application in C#
  • learned that code readibility is important through refactoring and mentorship
  • learned the efficient usage of version control systems
  • built a web application accessing Microsoft Azure Active Directoy via a REST API to manage users for one of our products
  • built a hybrid mobile application to let our customers monitor their machines status easily




Shortened apprenticeship for software development

September 2016 - January 2018

Oberstufenzentrum Informations- und Medizintechnik

During my time of the apprentice I was working for Publicis Pixelpark GmbH. There I built..

  • a REST API with the Spring Framework in Java
  • a web application with Node.js, Express.js and Handlebars
  • a command line application for our data team for automated transfer of social listening data

FH Aachen


ICT with specifics in application development [Incomplete]

August 2013 - August 2016

Aachen University of Applied Sciences

I learned about..

  • the basics of programming in C++
  • several other programming languages like Assembly, Prolog and Matlab
  • algorithms and data structures
  • IT security and forensic
  • databases and web technologies
  • computer systems architectures, operating systems and distributed systems

Bk GuT


IT assistant and advanced technical college entrance qualification

August 2010 - August 2013

Berufskolleg für Gestaltung und Technik

I learned about..

  • the basics of programming in C# and Java
  • web development with PHP and MySQL

A Little More About Me

I love creating things, solving puzzles, thinking about code and improving challenging problems. Open Source is what I like doing the most. I enjoy working in the community and sharing my knowledge with each other.

I also fell in love with the nature and the silence being out there. I like hiking, playing the piano and I am fascinated by the universe.