SuperiorCraft is an open source api that adds a configurable anticheat, custom blocks and items and much much more.
If you are going to use SuperiorCraft on your server, I strongly recommend building it yourself because the releases aren't all that recent.
The majority of the CustomBlock textures in the 'Customz' pack was created by CodeCrafted and can be found in their Block Designer and the the custom items were created by @superauguste.