I have done some work for different open source projects during my time at university and to a certain degree also after I started working. Currently I actively participate in one project with the permission of my employer in my free time.

I am also started some very small projects that are either not of much interest to a general audience or may be of interest, but nobody has found them yet (hint, hint!).

Large projects:

• vert.x (only small contribs yet, but I'm working on that)
• Jbehave (some contributions actually made it into the source)
• dokuwiki (minor contribution only)
• Jenkins (some fixes to the cvs plugin)

Small projects:

• vertx smtp mailer (not quite finished yet, this could become a contribution to the project)
• turtle graphics library (fork) for processing
• turtle graphics function for fabric.js (this was an entry for a competition, though I ended up 6 of 7 IIRC)
• dokuwiki_gtm Dokuwiki plugin for Google Tag Manager, basically the same as a Google Analytics tag for GTM supporting different tags and tag rules. Dokuwiki page is here

Previous contributions:

• gif2png (this is now maintained by someone else, I have not done anything with this since about 1996)
• pnmtopng (this is no longer maintained by me, but it ended up in netpbm, so it's in any Linux now)
• gnuplot (maintained that for a short while about 1995)

Other fun projects (mostly using open source components):

• monty hall game simulator page (souce for this is not yet published, if anybody is interested in the typescript source, let me know)
• pgp sender form send a mail to me with client-side encryption directly to my Evernote account. This project uses openpgpjs and encrypt.to to implement a form that encrypts the message for my pgp key before sending it to the server (the layout of the page uses the template from Jekyll, I was too lazy to find another one. I really should change that since it doesn't have anything to do with Jekyll except that the pages are generated with it)
• Mailtest test if your webmail or email clients leaks images that can be used to identify that you have opened the mail.