This is by far the most extensive and robust extension I have come across. To be able to develop a custom built database application through the joomla interface is amazing, and the product is free. I went free at first, and very quickly subscribed for the added features and support (which is great). The free product has paid for itself many times over and allows me, a non-programmer, to develop a custom built database application for our small company that would never have the budget to pay a developer to achieve the same results. Very extensive and versatile, and practically every time I conceive of something, I can find a way to do it through the interface.