Hello,
I am the highest rated Outlook Addin developer and I can develop your required Addin in a quick time. Please note that Web Addins have limited functionality and cannot achieve everything that a Desktop Addin can. I recommend to develop two separate versions, one for Desktop client and other for the Web client. Please take a look at my profile, past projects, clients feedback. Let's discuss project details over chat.
Thank you,
Usman