GIMP - GIMP is a multiplatform photo manipulation tool.
Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
Pixlr - Pixlr® makes it easy to transform everyday images into stunning works of art.
XnView MP - XnView is a free software that allows you to view, resize and edit your images. It supports more than 500 different formats!
Corel AfterShot Pro - Say hello to Corel AfterShot Pro 3, the world’s fastest photo workflow tool! Edit your photos up to 4x faster than Lightroom so you can spend more time behind the camera. Download a free 30-day trial today!
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.