It comes with a jsonlint tool which can be used to validate your JSON documents for strict conformance to the RFC specification; as it can also reformat them, either by re-indenting or removing unnecessary whitespace for minimal/canonical JSON output.
Complete documentation and additional information is available on the demjson project homepage.
It is also available on the Python Package Index, and can be installed using the Python distutils easy_install command.
Versions since 1.4 or newer are LGPLv3 (GNU Lesser General Public License, version 3 or greater). For older versions see the LICENSE.txt file in the source distribution.