I don't know as what you define free. But Qt is as far as I know is available under LGPL, GPL and under a commercial license. Also they co-operate with the KDE

I don't know as what you define free. But Qt is as far as I know is available under LGPL, GPL and under a commercial license. Also they co-operate with the KDE project and made sure that it will stay "free" IIRC.