GIMP - GIMP is a multiplatform photo manipulation tool.
ClippingMagic.com - Remove image backgrounds online. Make backgrounds transparent, white, etc. Edit, crop, rotate, fix colors, add shadows, all you need for great photos!
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
Icons8 Background Remover - Quickly remove the background from any photo
Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
Trace by Sticker Mule - Remove the background from any image for free