Tileable.co is offering the entire library of textures FREE (CC0) in 512px

Development Asset Creation
1

https://tileable.co is now offering all their textures for free at 512px resolution with direct download links!

(For ultra crisp HD versions the price has dropped too)

Edit: Updated wording for 512px - licence from non-commercial to CC0 (as of June 2018) !

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Regarding 512px being kinda useless - depends on the nature of the project, and how close the camera will be zooming in. I attached a rendered ball using one of the textures at 512px resolution. Tileable.co | Seamless Textures | PBR Materials