Unless someone from Intuit wants to chime in and give us current figures, there are different ways to estimate the number of businesses using QuickBooks:
In mid-2008, Intuit claimed that QuickBooks had 3.7 million users, representing 94.2% of the business accounting market.
A current Intuit webpage asserts that QuickBooks holds 85% retail market share in small business [...]
QuickBooks 2010 introduced something new: a suite of optional products/services that integrate into QuickBooks. There have been 3rd party solutions available for QuickBooks for years, but the difference here is that these new products/services live on the web.
They are accessible directly within the QuickBooks application, by clicking on the App Center button. You’ll see the [...]
Interview with Brian Sweat of Alterity, Inc. about developing inventory applications for QuickBooks. Their latest product, EZ Analytics for Inventory, is part of the Intuit App Center suite of 3rd party solutions.