you implement it on the serverside as an API or webapp that you sell as a service. There are many ways of doing this, for example resolver one, or ethercalc. In

you implement it on the serverside as an API or webapp that you sell as a service. There are many ways of doing this, for example resolver one, or ethercalc. In the olden days would have probably written a webapp that interfaced with excel directly using the COM APIs, but that went aggainst MSFT's EULA.