PicsArt - Explore 100,000,000+ awesome images and photos on the web
remove.bg - Remove the background of any image 100% automatically
Camera360 - Let those photos out of their albums and PK with Camera360 users worldwide!
ClippingMagic.com - Remove image backgrounds online. Make backgrounds transparent, white, etc. Edit, crop, rotate, fix colors, add shadows, all you need for great photos!
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.
Bg Eraser - Background Eraser on Mac and Windows.