The units.json.gz file contains one json document per line, rather than one json document in the file. The .json extension is misleading in this case.

It would perhaps be an improvement if the units.json file contained a single json object that had an attribute called 'units' with a list of units. Currently, the json parser cannot open the file:

$ python
Python 2.6.6 (r266:84292, May 27 2013, 05:35:12) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import json
>>> with open('units.json') as f:
...     a = json.load(f)
... 
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "/usr/lib64/python2.6/json/__init__.py", line 267, in load
    parse_constant=parse_constant, **kw)
  File "/usr/lib64/python2.6/json/__init__.py", line 307, in loads
    return _default_decoder.decode(s)
  File "/usr/lib64/python2.6/json/decoder.py", line 322, in decode
    raise ValueError(errmsg("Extra data", s, end, len(s)))
ValueError: Extra data: line 2 column 1 - line 82 column 1 (char 858 - 2527719)