UI Pixels is a gallery of free PSD's and Sketch app resources that you can download and use freely.
Free Mockup Envelope. You can easily use the design. Designed and released by Ruslanlatypov
App Design, Figma Resources, Free PSD
App Design, Free PSD
Free PSD, Sketch App Resources, Website Templates
Free PSD, Mockups
Free PSD, InVision Studio Resources