Who the market is actually using

Our other rankings answer “which is best”. These answer a different question: which platforms have the widest published adoption — regardless of what we think of them.

That distinction matters, so it is worth being blunt about it. Nothing in this section carries an OfficeBooks rating, and the order is not our opinion. Each entry is placed on signals its own vendor has published, and every number is linked back to the page that states it. Where a widely-repeated figure could not be traced to the vendor, we left the number out and said so.

There is no standardised, comparable usage metric across this market. Vendors publish whichever number flatters them — registered accounts, monthly active users, paying customers, enterprise logos — and those are not interchangeable. Treat the order below as a research shortlist, not a league table.