Trace by Sticker Mule - Remove the background from any image for free
Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
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.
Icons8 Background Remover - Quickly remove the background from any photo
Pixlr - Pixlr® makes it easy to transform everyday images into stunning works of art.