1. GIMP. Gimp is a powerful open source image editor that rivals Photoshop. It's available for both Windows and Mac operating systems.
2. Inkscape. Like Gimp, Inkscape is an open source program. Inkscape is a vector image editor similar to Adobe's Illustrator. It is available for Mac, Windows, and Ubuntu operating systems.
3. Pixlr. Pixlr is an online option for image editing. It's free and is pretty powerful offering many of the options found in desktop versions. Additionally it's also available for mobile devices.
4. Picmonkey. Pickmonkey does have a paid upgrade service available, however the basic model is very powerful as is. It has many fun filters, and options perfect for making images for blogs or social media.
5. Photoscape. Photoscape is a great tool for touching up photographs with tools like red eye removal, batch image editing and RAW to JPG conversion. It is only available on Windows.
You don't have to shell out the big bucks on an image editor. These free alternatives can meet a variety of needs. Did we miss your favorite free image editor? Let us know in the comments.