I'm a freelance software engineer with more than 15 years of professional experience, based in Berlin.
This page tries to sum up what I have been up to by now. Get in touch if you're interested in working with me, or check out the homepage for more information.
Employment
Senior Software Engineer at Wikimedia Jan 2023 → Aug 2024 (1 year, 8 months)
As a Senior Software Engineer at Wikimedia, I contributed to the development of Wikibase Cloud, a SaaS platform designed to empower users to create and manage their own customized Wikibase instances. My work involved designing, implementing, and optimizing features to ensure scalability, reliability, and ease of use for diverse communities, aligning with Wikimedia's commitment to open knowledge and collaborative data-sharing initiatives.
Senior Software Engineer at Field Intelligence Oct 2018 → Dec 2022 (4 years, 2 months)
As a Senior Software Engineer on the Platform team at Field Intelligence, I managed the infrastructure and contributed to the development of an offline-first application designed for supply chain management of medical goods in Nigeria and Kenya. In this role, I focused on building and maintaining the foundational systems that ensured the platform’s reliability, scalability, and efficiency, addressing the unique challenges of operating in regions with limited internet connectivity. My work helped enable the delivery of essential medical supplies to underserved communities.
Web Developer at Ecosia Nov 2016 → May 2018 (1 year, 7 months)
As a Web Developer at Ecosia, I contributed to the full-stack development of an eco-focused search engine that leverages the Bing API. My role involved working across the entire technology stack to enhance functionality, optimize performance, and ensure a seamless user experience.
Lead Frontend Developer at tracdelight Jan 2015 → Oct 2016 (1 year, 10 months)
As the Lead Frontend Developer at tracdelight, I led a team of developers in designing and building a modern, scalable replacement for an outdated legacy system. This involved guiding the team’s technical direction, ensuring high code quality, and fostering collaboration to deliver a user-friendly and maintainable frontend architecture. I also worked closely with stakeholders to align the project goals with business needs while mentoring team members to support their professional growth.
Frontend Developer at ShopLove Oct 2013 → Dec 2014 (1 year, 3 months)
As a Frontend Developer at ShopLove, I worked on enhancing and maintaining the frontend of a monolithic ASP.NET application. My contributions focused on improving the user interface, optimizing performance, and ensuring seamless integration with backend components. I collaborated closely with other developers to deliver a polished and functional product, addressing both technical challenges and user-centered design considerations.
Open Source
Offen Co-Author
Offen is a fair and open-source web analytics software designed to prioritize user privacy and transparency. As one of the two creators, I contributed to all aspects of the project, from concept and architecture to implementation and ongoing development. The project was funded by the NGI Initiative and NLNet, supporting its mission to provide an ethical alternative to traditional analytics tools by empowering users with greater control over their data.
https://github.com/offen/offen
docker-volume-backup Author
docker-volume-backup is a Docker image designed to securely and efficiently back up data from Docker volumes. With a focus on simplicity and reliability, it provides a streamlined solution for automating backup processes in containerized environments. As the sole author and maintainer, I actively manage its development, address user feedback, and ensure the project remains up-to-date.
https://github.com/offen/docker-volume-backup
mochify.js Maintainer
mochify.js is a test runner that enables developers to execute unit tests in headless browsers, making it easier to automate browser-based testing workflows. As an active maintainer, I contribute to the ongoing development and improvement of the project by collaborating with the wider maintainer community, addressing issues, and enhancing the tool to ensure it remains reliable and developer-friendly.
https://github.com/mantoni/mochify.js
Freelance
Freelance software engineer Jan 2025 → now
I use my generalist skillset to provide guidance and support to clients throughout all phases of their software projects. Recent work has involved migrating legacy self-hosted software to modern, scalable, and sustainable infrastructure solutions.
METERMADE Jan 2013 → Mar 2014 (1 year, 2 months)
As one of the founders of METERMADE, I developed, designed, and managed a web shop specializing in customizable furniture. The platform featured advanced configuration tools that allowed users to tailor furniture designs to their exact specifications. In addition to building and maintaining the technical infrastructure, I handled day-to-day operations, ensuring a seamless user experience and reliable e-commerce functionality for customers.
Interactive Developer and Animator Mar 2006 → Sep 2012 (6 years, 6 months)
As a freelance animator and developer, I contributed to a variety of projects in the fields of children’s television and education, often bridging the gap between creative animation and technical development. These hybrid roles required me to write code for interactive tools and applications while also producing high-quality animations to support storytelling and engagement. My work focused on blending artistry with technology to deliver compelling and educational content for young audiences.
Writing
Privacy focus? Consider the cookie Blog Post (2021)
An in-depth look at implementing cookies in a way that prioritizes user privacy and transparency, offering practical advice for balancing functionality with trust and regulatory compliance.
https://www.offen.dev/blog/privacy-cookies/
Untold Roads to v1.0 Blog Post (2020)
Insights and strategies for versioning early-stage software, exploring approaches to navigate the journey from initial development to a stable v1.0 release.
https://www.offen.dev/blog/untold-roads-versioning-early-stage-software/
Testing and testable JavaScript for absolute beginners and occasional programmers Blog Post (2018)
A beginner-friendly introduction to software testing in JavaScript, designed for self-taught programmers and occasional developers looking to build testable and reliable code.
https://blog.frederikring.com/articles/javascript-testing-for-beginners/
What I learned building an api.ai webhook Blog Post (2017)
A reflection on key lessons and practical tips gained while building a hobby project using api.ai (now Dialogflow), highlighting insights into working with conversational AI and webhooks in general.
https://blog.frederikring.com/articles/building-an-api-webhook/
Public speaking
Let’s end this arms race - with Hendrik Niefeld (2021/2022) Privacy Week Vienna 2021, FOSDEM 2022, COSCUP 2022 et al.
The talk examines the ongoing arms race between user privacy advocates and online data collectors. We explored how shifting from adversarial tactics to cooperative solutions could pave the way for a more privacy-conscious web, fostering collaboration between developers, organizations, and users.