Here was said All-in-one add-in for outlook that this is possible to create the web-based add-in working both with Mailboxes hosted on Office 365 or Exchange 2013 or greater, and with Outlook 2013 or greater, so with web and desktop Outlook versions.Am I right? Can you provide some references on how to develop such an add-in and then install it for both clients? Thanks you.
Best regards
You can start reading the Official documentation on Office add-ins. These new Office add-ins are web applications "served" inside Office products, you will have to be a little familiar with web technologies to develop.
Regarding Outlook add-in, as written by Eric Legault (in the question link), the add-in is not installed on a specific client but on the exchange account whether it is at organisation level or at user level. Consequently, with one install you will have the add-ins working on all Outlook clients (Desktop, OutlookWebAccess etc.).
Take care: Office add-ins now describes both technologies the new one that we are discussing (formerly app for office) and the old COM add-ins. I have written a blog post to explain the in-and-outs of the two technologies.
You are right. You have the opportunity to create a web-based add-in for Office 365 and Office 2013 desktop. But, Microsoft's JavaScript API has limited functionality. I want to recommend you read the following document first: https://msdn.microsoft.com/en-us/en-us/library/office/fp161015.aspx. If you plan to write a small add-in for yourself, the web-based add-in is a great option.
