Yandex.Images - search for images on the internet, search by image
Google Lens - Discover information about something by taking a photo
TinEye - Reverse Image Search to help find an image's source, duplicates or altered versions.
GImageReader - gImageReader is a simple Gtk/Qt front-end to the Tesseract OCR Engine.
SauceNAO - SauceNAO is a reverse image search engine.
OpenScan - FOSS Document Scanner