Flickr - image and video hosting website
Unsplash Wallpapers for Mac (Official) - Curated, HD desktop background photos from Unsplash.
Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
Irvue - (previously Unsplash Wallpaper) Gorgeous wallpapers on your Mac.
PhotoPrism.app - PhotoPrism® is an AI-Powered Photos App for the Decentralized Web. It makes use of the latest technologies to tag and find pictures automatically without getting in your way. You can run it at home, on a private server, or in the cloud.
Wallpaper Wizard - Wow-worthy backgrounds for Mac