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.
PackMojo - Create custom packaging in 3D and order in low volume
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.
Pakible - Custom packaging, made simple. 10 boxes for $10
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.
Die Cut Templates - Generate custom professional packaging templates in seconds.