UltraJSON is an ultra fast JSON encoder and decoder written in pure C with bindings for Python 2.5+ and 3.

For a more painless day to day C/C++ JSON decoder experience please checkout ujson4c, based on UltraJSON.

To install it just run Pip as usual:

$ pip install ujson

May be used as a drop in replacement for most other JSON parsers for Python:

>>> import ujson
>>> ujson.dumps([{"key": "value"}, 81, True])
'[{"key":"value"},81,true]'
>>> ujson.loads("""[{"key": "value"}, 81, true]""")
[{u'key': u'value'}, 81, True]

Used to enable special encoding of "unsafe" HTML characters into safer Unicode sequences. Default is False:

>>> ujson.dumps("<script>John&Doe", encode_html_chars=True)
'"\\u003cscript\\u003eJohn\\u0026Doe"'

Limits output to ASCII and escapes all extended characters above 127. Default is true. If your end format supports UTF-8 setting this option to false is highly recommended to save space:

>>> ujson.dumps(u"\xe5\xe4\xf6")
'"\\u00e5\\u00e4\\u00f6"'
>>> ujson.dumps(u"\xe5\xe4\xf6", ensure_ascii=False)
'"\xc3\xa5\xc3\xa4\xc3\xb6"'

Controls whether forward slashes (/) are escaped. Default is True:

>>> ujson.dumps("http://esn.me")
'"http:\/\/esn.me"'
>>> ujson.dumps("http://esn.me", escape_forward_slashes=False)
'"http://esn.me"'

Controls whether indention ("pretty output") is enabled. Default is 0 (disabled):

>>> ujson.dumps({"foo": "bar"})
'{"foo":"bar"}'
>>> ujson.dumps({"foo": "bar"}, indent=4)
{
    "foo":"bar"
}

UltraJSON calls/sec compared to three other popular JSON parsers with performance gain specified below each.

Linux 3.13.0-66-generic x86_64 #108-Ubuntu SMP Wed Oct 7 15:20:27 UTC 2015

• CPython 2.7.6 (default, Jun 22 2015, 17:58:13) [GCC 4.8.2]
• blist : 1.3.6
• simplejson: 3.8.1
• ujson : 1.34 (0c52200eb4e2d97e548a765d5f089858c41967b0)
• yajl : 0.3.5

• CPython 3.4.3 (default, Oct 14 2015, 20:28:29) [GCC 4.8.4]
• blist : 1.3.6
• simplejson: 3.8.1
• ujson : 1.34 (0c52200eb4e2d97e548a765d5f089858c41967b0)
• yajl : 0.3.5