Photopea - Online photo editor, which can work with PSD, XCF and Sketch files (Photoshop, Gimp and Sketch App).
Contra Wireframe Kit - Open source wireframe kit for design and prototyping 🚀
Replace Cover - Create beautiful cover art for your Spotify playlists
Platforma - Wireframe library of layouts and UI elements
Headers.me - Create social cover images that get you followers
Craftwork - A collection of User Interface resources made by Craftwork