Want to work with upstream Free Software developers?

Like everybody in the industry, you are using Free Software all over the place. Some of it works right out of the box, while some of it needs modifications so it can fulfill your requirements. But managing these modifications yourself is painful. Every time you need to debug or upgrade anything, you have to integrate your changes all over again. It would be much easier if you could get your developments and customization accepted into the upstream code base. Then they would be managed and maintained by the Free Software community, and you would never have to reintegrate them yourself.

This is exactly what I can help you with.

I have participated in a lot of Free Software projects over the last years and worked for lots of different companies: I have a very good knowledge of the Free Software and Open Source ecosystems.

My involvement and ability to work with upstream software authors and teams have tuned my development mindset to keep upstream merging in mind, so the code will be acceptable for being contributed back and adopted, to be maintained and supported by the community later.

If you're interested in talking about how I can help you merge your work into upstream software projects, just drop your e-mail address below and I'll get back to you.

If you want to learn how I've been able to help my customers so far, check out my references.

Software development

Whether you're thinking about enhancing an old project or building a new one using Free Software or Open Source technologies, I can help you. Especially if it's C or Python based!

Linux System Expertise

Being a Debian developer for more than 12 years, I know a bunch of things about Linux systems and development on this platform (and therefore on Ubuntu). And I did years of system administration and technical support on Linux.

Cloud computing

Going to the cloud? I have built entire cloud platforms, and I'm an OpenStack developer. My expertise can help you make good choices, deploying or enhancing your own cloud services.

Team player

I have worked for several companies, schools, R&D international software collaborations, on site and remotely. With teams of widely varying size and culture.

You can contact me directly by e-mail or via this form.



Since 2011 Free Software Consultant at Julien Danjou (Paris, France)
  • Upstream contributions to OpenStack;
  • Free Software development;
  • Information Technology consulting.
Fore more detail, you can check my references.
October 2011 - June 2012 Lead developer at eNovance (Paris, France)

eNovance is a cloud and managed service provider.

February 2006 - September 2011 Linux system engineer at Easter-eggs (Paris, France)

Easter-eggs is a computer service company providing Free Software only based solutions.

  • Specification, integration and deployment of Debian GNU/Linux based servers (LAMP, proxy, e-mail, firewall etc) for 40+ customers
  • Administration and development on Debian GNU/Linux systems
  • Various Free Software code hacking (C, Python, Perl)
  • Consulting, audit of running Linux systems: resolution of performance problems, detection of bad practices
  • Development of custom Debian GNU/Linux distributions and installers
  • Set-up and management of customer datacenter hosting (all technical and financial sides)
  • Building of cloud based hosting solution for big and ephemeral events (scaling, tests, etc)
June 2005 - August 2005
April 2003 - June 2003
System and network administrator at Lost Oasis (Marseille, France)

Lost Oasis is an Internet service provider (AS29075)

  • Administration and technical support on the main hosting platform
  • Network backbone administration, troubleshooting
  • Network and system monitoring tool set-up
June 2003 - August 2003 Quality assurance developer at Mandriva (Paris, France)
  • Hardware certification kit development (Perl)
  • Internal developments for the R&D department


Since 2011 OpenStack
Since 2010 GNU Emacs

Developer. Working on Gnus (an e-mail and news reader), Org-mode (organization tool) and various other packages.

  • Developed the google-maps and google-weather packages to get access to Google Maps and Weahter directly from Emacs
  • Imagined and implemented an algorithm to enhance foreground and background colors contrast in text rendering based on CIE DE2000
  • Wrote several packages (Gravatar, rainbow-mode) and contributed to tens of others.
  • Co-maintainer of el-get, Emacs extensions installation system (2011-2013)
  • Maintenance of the emacs-snapshot packages for Debian
Since 2008 Freedesktop
Since 2007 awesome

Author and technical leader of awesome, a X11 window manager, written in C and XCB and embedding Lua as its configuration language.

Since 2002 Debian


Since 2001 Free Software

Various contribution to multiple Free Software projects, like:

November 2008 CVE-2008-5187

Report of an Imlib2 vulnerability.

2003 - 2009 Ornix

Co-founder and active member of the Linux User Group of the Orne department. Event organization (Linux install party).

2002 - 2006 TuxFamily

President and system administrator.

  • Team work with other system administrators
  • Development and administration of the hosting platform (12 servers)
  • Organization management
2001 - 2006 VHFFS

VHFFS is a massive hosting platform and I've contributed to the development of the version 1, 2 and 4.

2000 - 2002 Frag Arena

Founder, president and network administrator.

  • Organization management
  • LAN party organization
  • Ephemeral network administration
1999 - 2002 Linux En Rezo / SANS Linux

Linux En Rezo (literally "Linux on network") was a french website aiming to help people wanting to set up their own home-network. I wrote a lot of documentation about installing services like DHCP, Samba, BIND, Apache, etc…


2004 - 2006 Master in Computer Science, System and Network Administration and Exploitation at University of South Brittany (Vannes, France)
2003 - 2004 Bachelor in Mathematics and Computer Science at University of South Brittany (Vannes, France)
2001 - 2003 University Diploma in Technology, Computer Science at Le Havre Institute of Technology (Le Havre, France)

eNovance: Ceilometer development

eNovance is an hosting and cloud provider company. In 2012, I leaded their development team to build the first European cloud based on OpenStack.

Later, while enhancing its cloud platform solution, eNovance needed an accounting solution for OpenStack. They chose Ceilometer, and hired me to contribute to the project and center efforts on features required for their deployment to succeed.

Julien is a great expert in Python development, an well known OpenStack specialist and one of the lead architect on Ceilometer (metering for OpenStack) since the beginning of the project. I have collaborated with Julien on Ceilometer since the beginning of the project and more recently have been hiring him to help eNovance develop additional feature on Ceilometer for our customers. He has always delivered above and beyond my expectations. I would not recommend you to hire him, though, as I'd like to keep him focused 100% on his collaboration with us :) Nicolas Barcet, VP Products

DreamHost: Ceilometer features implementation

DreamHost is a Web hosting company that launched a cloud computing offer in 2012 based on OpenStack. Like any cloud platform operator, they needed accounting features in order to bill properly they customer.

Rather than reinventing the wheel, they chose to participate in the developement of Ceilometer, the OpenStack Metering project to build their solution. I've been in charge to implement features they needed directly into Ceilometer.

I have worked with Julien on Ceilometer, a part of the OpenStack project. We started our collaboration when the project was created in 2012, and when Julien started freelancing later that year we hired him to work on some features that were a priority for DreamHost. He is an excellent developer; his designs and implementation are always solid. I would not hesitate to work with Julien again in the future. Doug Hellmann, Senior Cloud Engineer

Talligent: Ceilometer consulting

Talligent develops an open billing system built for the cloud. They would like to support OpenStack, so I've been able to help them deploying a development platform and give them advice about using Ceilometer for their needs.

Julien delivers. I engaged Julien to help us kickstart Talligent's OpenStack integration and to consult with us on his Ceilometer implementation. Julien stood up our first OpenStack network and performed all the configuration required for our software to integrate with the network. He did this remotely and with minimal supervision and was highly responsive and informative as we had questions and issues. I enthusiastically recommmend Julien for his OpenStack and virtualization expertise - I believe we saved several months of effort by hiring him - and I hope to have the opportunity to work with him again. Sanjay Mishra, Founder, Principal architect

SwiftStack: developments for Swift

SwiftStack is a company editing a storage system based on Swift, the OpenStack Object Storage project.

SwiftStack already works with and employs some upstream developers of Swift, and I've been able to help them adding new features on Swift and the SwiftStack software stack.

Smile: OpenStack consulting

Smile is an open source solution integrator, and chose to work with OpenStack for their cloud solutions.

I've been able to help them working with upstream developers, fixing bugs, providing advice and training for people to interact with the community.

EISTI: Ceilometer development

EISTI is a Computer Science engineering school, and takes part in the XLCloud project. XLCloud aims at bringing High Performance Computing (HPC) to the cloud, using OpenStack.

A part of the project is about accounting the platform usages, for the IaaS and PaaS sides of the developed solution. I've been able to provide advice on Ceilometer usage and how it could be helpful to the project, along with orienting and doing some upstream development on Ceilometer.

SmartJog: Debian packaging training

SmartJog provides media solutions to their customers. Their architecture relies heavily on Debian.

I've been able to provide them training sessions around the Debian packaging workflow, and how they could work closer with upstream to leverage and optimize their work.

1984: OpenStack setup

1984 is an hosting company established by free software and civil rights enthusiasts. To modernize their infrastructure, they were looking at deploying an OpenStack platform.

After discussing their requirements, I've been able to build a small OpenStack platform for them, while fixing some bugs encountered during the setup directly in the upstream code base.

Other companies I helped along the years

VoIP set-up, LAMP platform system audit and administration.

Git expertise, development workflow consulting.

Set-up of fail-over and load-balanced HTTP proxy using Squid, replicated virtualization server using libvirtd for HQ.

Scalable LAMP hosting on cloud platform for the Nuit Blanche 2010 and Paris-Plages websites.

Management of the LHEO project, set-up of a fail-over Web platform.

Development of a custom Debian GNU/Linux distribution for thin-clients, with inventoring agent.

Linux systems audits and administration.

Linux systems administration, infrastructure virtualization.

Linux systems administration, development of automation scripts and custom system administration applications.

IPBX set-up and programming to automate calls dispatch using Asterisk.

Debian GNU/Linux servers farm administration.

Debian GNU/Linux servers and firewall set-up and administration.