Paste JSON and get a Python dict literal you can drop straight into your code - None, True/False and 4-space indents.
JSON with double quotes, true, false and null - none of which Python will accept if you paste it straight into a .py file.
A dict literal that runs as-is, with the JSON keywords translated and the nesting indented the way Python code is normally written.
Saves a find-and-replace pass that is easy to get subtly wrong.