Is there some small web server that can be installed on several platforms that can just interpret my cgi and fork the processes, independently from the presence of Apache or something else?

Although there are small httpds available for either platform, I don't know of one that supports both. Brewing up your own with HTTP::Daemon could quickly turn into a large project.

Have you considered bundling your own minimal distribution of Apache? This would certainly work on Unix where you can easily have two Apache servers running. I suspect you could do the same on Windows. (Can someone else say for sure?)

This would solve the very messy problem of trying to find an existing web server and making your stuff work nicely with it. Besides, as your software already runs on Apache, you wouldn't have to waste effort on making the transition to another server platform.

-sauoq
"My two cents aren't worth a dime.";