This is a list of the more mature Open Source projects in which I have/had a major involvement. Several other projects are on Github.
Objective-C / OS X / iOS
OCMock is an Objective-C implementation of mock objects. Thanks to the powerful Objectice-C runtime only 200 lines of code in two classes were required to implement a fairly complete mock object library. A few years and a few more features later we’re at several thousand lines, though.
CCMenu displays the build status of projects on a continuous integration server as an item in the Mac’s menu bar. Or in other words, CCMenu is to OS X what CCTray is to Windows. And in case you are wondering: of course it is prettier.
C# / Microsoft .NET
Neo is a framework for .NET developers who want to write enterprise applications with an object-based domain model. It is well suited for domain-driven design and agile development. Neo includes tools that create an extensible object-based domain model as well as the database schema from a an abstract description of the model. At runtime, rich schema information is used to dynamically generate all SQL required for object persistence management.
Objective-C / Cocoa / GNUstep
A collection of frameworks for Mac OS X, GNUstep and WebObjects. The Common framework provides advanced datastructures, socket wrapper classes, a lightweight XML DOM implementation and other goodies. The Message framework covers internet messages (in the sense of email and usenet postings) and the Style Sheet framework is a templating engine.
A little application to display logfiles on your Mac desktop. The main reason for writing and publishing MkConsole was my continued frustration with the Mac OS shareware mentality. How can people work on an operating system that got so much from the Open Source community and then make a piece of software that can be written in a weekend shareware? How can we expect to see lots of great software on the Mac when a lot of promising software is closed source and cannot be improved by the community? I will probably write a longer article soon explaining why I think the $5 shareware mentality hurts Mac OS X.
I came across WordNet while writing my thesis and since there was no client for the platform I was using at the time I wrote one. In the following year Marcus did a great job porting it all the way to Mac OS X.
After the success of our Usenet newsreader Alexandra (see below) Constantin and I decided to write a new one for OPENSTEP, an operating system that would become Mac OS X. We did get quite far but at some point had to admit that neither of use was reading Usenet news anymore and neither of us would have the time to support a high-profile end-user application. We are looking for new developers who are interested in putting the finishing touches on the application and then releasing it. Read the appeal.
Around Christmas 1997, Marcus and I were looking for a decent OpenSource bugtracker for use at Object Factory, the company we worked for at the time (RIP). All we could find was Gnats. With the usual optimism and naivity we decided we could write one in the week between Christmas and New Years and delivered about 3 months later. The application was really slick and was used in various companies but in the end the developer community was too small for such a system.
In 1995 Constantin asked me whether I wanted to join him in his effort to write a good newreader for the NeXTSTEP platform; something that was desperately needed at the time. A while later we released version 0.8 which became a huge success and was at times the most popular newsreader for NeXTSTEP.