A testbed is a platform for experimentation of large development projects. Testbeds provide a means of rigorous, transparent, and repeatable testing of scientific theories, computational elements, and other new technologies.

The term is used in several disciplines to describe a development environment that is protected from the risks of testing in a production environment. It is a method of testing a particular module (function, class, or library) in isolation. It can be implemented as a test environment "Sandbox (computing)"), but not necessarily for the purpose of security verification.

A testbench is used when a new module is tested separately from the program to which it will later be added. A skeleton framework is implemented around the module so that the module behaves as if it were already part of the larger program.

Testbeds are also pages on the Internet where the public has the opportunity to test CSS or HTML code to see the result.