This is a user interface for the command line tool OCRmyPDF.
It's main purpose is to provide users that are not used to command line tools access to OCRmyPDF's basic features.
You can use it to make PDF files that contain images with text (e. g. after scanning) searchable by adding an invisible text layer.
It supports more than 100 languages "out-of-the-box" (all languages that are installed with tesseract).
Be sure to switch on "Read/write on removable storage devices" in the permission settings!
If you like the results created with OCRthyPDf but need more flexibility I suggest you give OCRmyPDFa try on the command line (https://github.com/jbarlow83/OCRmyPDF/) . :)