It is pure Python code with no dependencies, but includes an optional C extension for a serious speed boost. The encoder may be subclassed to provide serialization in any kind of situation, without any special support by the objects to be serialized . The decoder can handle incoming JSON strings of any specified encoding . simplejson is the externally maintained development version of the json library included with Python 2.6 and Python 3.0, but maintains backwards compatibility with Python 2.5. It gets updated more regularly than the json module in the python stdlib.