There is a task: add the ability to work with MS Office documents (particularly Word and Excel) to your service. You need to give the user the option to upload a document and then edit it already in my website.
Saw a similar integration into Yandex Disk and Cloud Mail.ru however, I can not understand how they did it, because surely they pay some royalties (probably not small) to Microsoft.
In General, advise any solution if not then maybe some pay but with an adequate value. Here is
what I would like to see