Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
picinfinity - Picinfinity is an image retaining/proxy site.
Picorator - Picorator is a simple yet powerful image sharing application developed by online communities.
imgbox - Imgbox is a free image hosting service.
Libris - Libris is an asset management for photos and videos.
ImgBB - Upload and share your images.