This nifty set of free credit card icons was designed and shared by Arthur Koch. Nice work!
A Style Free ECommerce UI Kit. This UI Kit was originally created for rapid prototyping on behalf of FORM Agency and has now been put together to be downloaded for free.
Here's an interesting Minimal UI Kit created with Sketch. This ui kit comes with clean design, well organized elements and editable content.
Free iPhone X Minimal Mockup for Sketch. Feel free to use it for your own projects and presentations. iPhone X Minimal Mockup freebie was designed by Eduardo Higareda
Free - Social UI Kit that he has created some time ago. The UI design looks clean and modern, with a well suited color scheme by Alex Gilev