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. I have also made contributions to APR, Apache HTTPD, and Apache Serf.


Contributions to Osmocom, 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:

  • Forge a lasting relationship with communities building the software you rely on
  • Devise the best strategy to open-source an existing product
  • Build a new open source community around your project
  • 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!

Ich biete OpenBSD Schulungen und Support auch auf Deutsch an.

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
    • Osmocom developer (2018 to present)
    • 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.

PGP: 8BC4 DAE0 C5A4 D65F 4044 0107 4F7D BAA9 9A59 B973