Stefan Sperling - FOSS Developer and Consultant

Freelancer based in Berlin specializing in Free and Open Source Software

FOSS: Free and Open Source Software
Software which can be used, shared, and modified freely.


I develop software for businesses and non-profit organisations, drawing on experience as professional and volunteer contributor to free and open source software projects.


The OpenBSD project develops a UNIX-like general purpose operating system which is free, functional, and secure.

My areas of contribution include device drivers, IPv6, UTF-8 support, and wireless networking. I help with porting existing software to OpenBSD and developing OpenBSD-specific software.

Apache Software Foundation

The Apache Software Foundation (ASF) is a US 501(c)(3) non-profit corporation supporting open source communities using a collaborative development model. Over 130 ASF projects cover a wide range of frameworks and applications which enjoy wide use within the industry.

As an active ASF member I work with and for ASF projects and do my part in shaping the future of the ASF.

I have been contributing to the Apache Subversion project for almost a decade.


Contributions to xfce, gnome, e17, pulseaudio, python, freebsd,, OTR ...

I will consider work proposals involving any project in the free software community.


I provide advice and training in FOSS development methods for businesses getting involved with open source communities. Problems I can help solve include:

  • Improving your relationship with communities building the software you rely on
  • Devising the best strategy to open-source an existing product
  • Building a community around a new project idea

In cooperation with Berlin-based company elego I offer support and consulting services for the Apache Subversion version control system.

OpenBSD end-user services such as support for system setup, configuration, deployment, and advice on picking hardware and software for products based on OpenBSD are available on request.


  • Professional Focus
    • Open Source developer and consultant
    • Software development process consulting and tool support
    • Workshops and trainings for developers and end users
  • Projects
    • OpenBSD developer (2008 to present)
    • Apache Subversion developer (2007 to present)
    • Consulting services around Apache Subversion (2008 to present), with elego

Download complete curriculum vitae in PDF format


Stefan Sperling

I am fluent in English and German.