I really like the idea of Foxytag. The principle is very simple and logical, someone just had to do it, so thank you for doing the work.
But before using and promoting your software I'd want to know if it's really going to remain free.
On your homepage you state in the FAQ that Foxytag is an "academic non-profit project". But this is no legally binding guarantee Foxytag will remain free.
Why not make it Open Source and release it under a Free Software license like GPL and thus assuring no competitor can commercially benefit from your work?
Too many software that has been previously declared as free is now on sale. If you're serious and honest about remaining free you should put your software under a Free Software license, even if not Open Source, and that way earn the trust and support of your users.
Best Regards,
Viktor Trojanovic