We are looking to integrate our web application (a capture component) into Sharepoint Online. The idea is that the user will be loading our app and have the ability to either open an item from a document library directly into it for editing (i.e. rearranging pdf pages) or scan a new document into our app and then directly save it into his Sharepoint doc library.
We are looking for advice on what is most appropriate for this, web part or add-in? Hosted or Provider add-in? It would be best if the user is able to add it in his site just like a Custom List for example.
We are not familiar with C# so avoiding writing aspx code is a plus but only if the same functionality can be otherwise achieved.