Vendor lock-in

In economics, vendor lock-in, also known as proprietary lock-in or customer lock-in, makes a customer dependent on a vendor for products and services, unable to use another vendor without substantial switching costs. Lock-in costs which create barriers to market entry may result in antitrust action against a monopoly.

The European Commission, in its March 24, 2004 decision on Microsoft's business practices, quotes, in paragraph 463, Microsoft general manager for C++ development Aaron Contorer as stating in a February 21, 1997 internal Microsoft memo drafted for Bill Gates: "The Windows API is so broad, so deep, and so functional that most ISVs would be crazy not to use it. And it is so deeply embedded in the source code of many Windows apps that there is a huge switching cost to using a different operating system instead. It is this switching cost that has given customers the patience to stick with Windows through all our mistakes, our buggy drivers, our high TCO, our lack of a sexy vision at times, and many other difficulties. [...] Customers constantly evaluate other desktop platforms, [but] it would be so much work to move over that they hope we just improve Windows rather than force them to move. In short, without this exclusive franchise called the Windows API, we would have been dead a long time ago. The Windows franchise is fueled by application development which is focused on our core APIs"

Microsoft's application software also exhibits lock-in through the use of proprietary file formats. Microsoft Outlook uses a proprietary, publicly undocumented datastore format. Present versions of Microsoft Word have introduced a new format MS-OOXML. This may make it easier for competitors to write documents compatible with Microsoft Office in the future by reducing lock-in. Microsoft released full descriptions of the file formats for earlier versions of Word, Excel and PowerPoint in February 2008.

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