Hi Sir/Madam,
I have been working with Office development for 8 years. I have experience with Office addin/plugin.
I developed many addin/plugin for Outlook, Excel, Project, Word as application based or document based like work item management(outlook), project document management(outlook), task health checker(project), invoice management(excel), article integration with inhouse application(word). I used the Sharepoint, SQL, One drive as datasource. You can check my freelancer profile to see some plugins.
Please let me know if you have any questions.