Docr - Docr is a free app for the iPhone smartphones that lets its users scan all of their documents into sharp images and, in the end, store them as PDF files.
Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.
Scanner Pro - Scanner Pro turns your iPhone into portable scanner in your pocket.
Joplin - Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, tagged and modified either from the applications directly or from your own text editor.
DocScan - DocScan is a PDF document scanner application for the iPhone smartphones that lets the users to scan their documents and get them in the PDF files.
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.