If you want totally free product, you shall consider products that are not backed by a corporate, such as Wicket. As a corporate, it has to make money. Otherwise, it won't be able to support the continual investment on the product. Some versions are free. Some are not. It is quite OK to me. Spring and many others have the similar model. Vaadin mentioned by GuyDenruyter has the same model: they made money from addon (GPL/CVL), though they claim Vaadin is free. Again, it makes sense to me.
ZK - Open Source Ajax Java Framework
If you want totally free product, you shall consider products that are not backed by a corporate, such as Wicket. As a corporate, it has to make money. Otherwise, it won't be able to support the continual investment on the product. Some versions are free. Some are not. It is quite OK to me. Spring and many others have the similar model. Vaadin mentioned by GuyDenruyter has the same model: they made money from addon (GPL/CVL), though they claim Vaadin is free. Again, it makes sense to me.