Now you can. OnlyOffice has been opensource since October 2016. That means you know exactly what the code is AND that it can be hosted directly for you for just $5/month. Learn more at…

https://www.onlyoffice.com/

You get documents, mail, a CRM, projects, a calendar, and community tools too. See comparisons with other office suite products (hover over “Apps” in the top-line menu then choose “OnlyOffice Alternatives.” They now claim to be the world’s #1 suite! Plus, you can download the entire suite and host it on your own server for free! Why WOULDN’T you want to try it?