The numerical tools implement numerical methods, and include sparse linear system solvers, ODE solvers, etc. Developer support tools provide a infrastructure for tool developers and probably will not be used or seen directly in scientific applications. Extensive information on the individual tools is provided on this web site, underneath the Tool Descriptions page. ACTS tools are freely available to non-commercial users. Some are available without restrictions and some require you to sign a non-redistribution agreement.
Source is usually available.
Some ACTS developers also provide support directly. The ACTS project originated as subset of the former DOE 2000 project which had two main components, the ACTS Toolkit and the National Collaboratory project. A third part of DOE 2000, the collaboratory pilot projects, was in some sense a testbed for the Collaboratory project. The first two parts of DOE 2000 were related in that they both enhance the ability of DOE scientists to solve major scientific and technical problems. Increasingly, these problems involve multiple, complex subproblems that often span several disciplines, requiring scientists from multiple disciplines to work closely together.