Mozillian のプロファイル
Mozillian 歴 6 年 Sep 2013
United Kingdom
21:32 Europe/London
IRC : costenslayer

Stefan Costen

Breaker of things @ Mozilla Community Web Services


Stefan is known on the Internet as Costenslayer and has used this name for many years and as a result its origins are now lost.

He manages the MozillaUk twitter account

He also help's with Community Operations (IT) with hosting requests ...and more

He additionally help run makerparty's and the yearly MozFest in London as a volunteer since 2014, were he made an awesome fox mascot check this photo out photo

See his blog post on volunteering at MozFest 2014.

He’s also overseeing the Youth Mozilla (YoMo) mentorship program inspiring young people to contribute to the Mozilla mission and use open source software see his blog on follow how YoMo is growing on his blog.

He is also very active on twitter promoting Mozilla’s latest public announcement and news as well as quirky quotes see his twitter

he also help out with the SuMo (support mozilla) community helping users with there issues as well as AoA (Army or awesome) which is Support for Mozilla

see his Sumo profile

Finally he is also available on twitter over many channels you can find him in #Mozillians as the user Costenslayer


Access Groups

nda, mcws team, slack-access


blogger, bitcoin, mozfamily, mentor, mozfest, webmaker, sf-monument, mozilla guides, support, communityit, buddies, sumo, it, education, engagement, firefox student ambassadors, marketing, firefoxos, flame users, community management, community builders, mozfest volunteers, moco


blogging, computer hardware, events organisation, facilitating events, html, java, linux, public speaking, running events, server admin, social media, social networking, technical support, ubuntu, webmaker






  • Mark Surman

    Stefan has shown a great deal of initiative in figuring out new ways to bring youth into Mozilla. We need more of this.

  • Sarah Allen

    One of the volunteer heroes of Mozilla Festival who bring their unique skills and dedication to the festival each year to make it the success it is today. Stefan is an entusiastic team player who has worked across many areas of the festival.

  • Luis A. Sanchez Romero

    Stefan Is an extraordinary Mozillian, this year he help at Mozfest as volunteer always happy to help the sessions.

  • Laura Hilliger

    Stefan has helped with live train the trainer events and is always willing to help people find their way in IRC channels and via various lists.

  • Michelle Thorne

    I've met Stefan and he's helped run a training for Webmaker Mentors. He's a great guy and very dedicated Mozillian.

  • Tom Farrow

    Stefan is a youth mentor at EPIK. He helps teach kids in kent how to code, ultimately building towards the goals of webmaker.


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