The ScanEasy app allows you to scan documents, photos, and even QR codes. You can choose the quality of the scan and also edit or crop the image as you wish. Once you're done scanning, you can save it in a number of file formats, including PDF.

This is a free, simple, and fast app. You don't need to install anything else. All you need is a smartphone with a built-in camera to scan your documents and photos.

The best part is that you can use this app as a PDF converter and also convert your images to PDF.