Stefan Sperling - Developer and Consultant

Free and Open Source Software Development and Consulting

Become part of the FOSS community with professional guidance
Based in Berlin, working anywhere in Europe


I develop software for businesses and non-profit organisations, drawing on experience as professional and volunteer contributor to various 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 port existing software to OpenBSD and write OpenBSD-specific software.

Apache Software Foundation

The Apache Software Foundation (ASF) spans over 130 projects covering a wide range of frameworks and applications enjoying wide use within the industry.

As an ASF member I do my part in shaping the future of the ASF. I have been contributing to the widely-used Apache Subversion version control system for over a decade.


Contributions to git, XFCE, Gnome, e17, Pulseaudio, Python, FreeBSD,, OTR, ...

I will consider any project proposals involving free and open source software.


I provide advice and training in open source development on topics such as:

  • Integrate open source software into products
  • Build an open source community around your project
  • Forge a lasting relationship with open source communities
  • Receive code review and mentoring for developers freshly exposed to open source

OpenBSD end-user support for setup, configuration, deployment, and maintenance is available on request. Your firewalls have never been happier than this!

Together with elego I offer support and consulting services for the Subversion version control system.


  • Professional Focus
    • Open Source developer and consultant
    • Software development process consulting and tool support
    • Workshops and trainings for developers and end users
  • Projects
    • OpenBSD support (2015 to present)
    • OpenBSD developer (2008 to present)
    • Support and consulting services for Apache Subversion (2008 to present), with elego
    • Apache Subversion developer (2007 to present)

Download curriculum vitae


Stefan Sperling

I am fluent in English and German.