CowboyRobot writes "Intuit launched QuickBooks in 1992, and it has grown into the best-selling retail software for small-business accounting worldwide. QuickBooks is available on multiple platforms with different feature sets (Pro, Premier, Enterprise), in specialized editions (accounting, contracting, etc.), is available on CD or via subscription, and is offered in localized versions for the U.S., Canada, and the U.K. How they manage so many builds is a case-study for large scale programming. 'The Windows version is about 80,000 source files, 10+ million lines of C++ code plus a little C# for the .NET parts. Plus help files, tax tables, files defining local accounting rules, tax and other government reporting forms, upgrade offers — a lot of files. Every customer gets the full version. Specific feature sets are turned on and off with the license key.' And the lessons are not just technical. 'One surprising lesson is that small teams work, even for very large codebases — especially, Burt says, in sustaining an entrepreneurial, creative culture.'"