Rational ClearCase is a software tool for revision control (configuration management, SCM etc) of source code and other software development assets. It is developed by the Rational Software division of IBM. ClearCase forms the base of version control for many large and medium sized businesses and can handle projects with hundreds or thousands of developers, but the price is quite steep for smaller companies.
Rational supports two types of SCM configurations, UCM, and base ClearCase. UCM provides an out-of-the-box SCM configuration while base ClearCase supplies only the basic tools. Both can be configured to support a wide variety of SCM needs.
ClearCase can run on a number of platforms including Linux, Solaris and Windows. It can handle large binary files, large numbers of files, and large repository sizes. It handles branching, labeling, and versioning of directories.