Darktable - darktable is an open source photography workflow application and raw developer.
Icons8 Background Remover - Quickly remove the background from any photo
Adobe Lightroom - Adobe Lightroom is a family of image organization and image manipulation software.
IMG.LY - Power Your Apps with IMG.LY | The Leading Provider of Design, Photo, and Video Editing SDKs
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.
ClippingMagic.com - Remove image backgrounds online. Make backgrounds transparent, white, etc. Edit, crop, rotate, fix colors, add shadows, all you need for great photos!