TinEye Reverse Image Search 

TinEye Reverse Image Search is a browser extension that allows you to find out where an image came from, how it's used, or find higher resolution versions. When you submit an image to be searched, TinEye creates a unique and compact digital signature or 'fingerprint' for it, then compares this fingerprint to every other image in our index to retrieve matches. TinEye does not typically find similar images; it finds exact matches including those that have been cropped, edited or resized.