TinEye
Reverse Image Search
TinEye is a company that specializes in reverse image search and recognition. The service allows users to search over 76.6 billion images to find where a specific image appears online. The company also offers various products and solutions for businesses, including the TinEye API, MatchEngine, TinEye Alerts, WineEngine, and MulticolorEngine. The technology is based on computer vision, pattern recognition, neural networks, and machine learning.
I'm surprised I haven't featured this excellent service before.
Website Description
Search over 76.6 billion images and find where images appear online. Using TinEye is private and we do not save your search images.