# UltraJSON
[](https://pypi.org/project/ujson)
[](https://pypi.org/project/ujson)
[](https://pypistats.org/packages/ujson)
[](https://github.com/ultrajson/ultrajson/actions)
[](https://codecov.io/gh/ultrajson/ultrajson)
[](https://zenodo.org/badge/latestdoi/1418941)
[](https://github.com/psf/black)
UltraJSON is an ultra fast JSON encoder and decoder written in pure C with bindings for
Python 3.7+.
Install with pip:
```sh
python -m pip install ujson
```
## Usage
May be used as a drop in replacement for most other JSON parsers for Python:
```pycon
>>> import ujson
>>> ujson.dumps([{"key": "value"}, 81, True])
'[{"key":"value"},81,true]'
>>> ujson.loads("""[{"key": "value"}, 81, true]""")
[{'key': 'value'}, 81, True]
```
### Encoder options
#### encode_html_chars
Used to enable special encoding of "unsafe" HTML characters into safer Unicode
sequences. Default is `False`:
```pycon
>>> ujson.dumps("<script>John&Doe", encode_html_chars=True)
'"\\u003cscript\\u003eJohn\\u0026Doe"'
```
#### ensure_ascii
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:
```pycon
>>> ujson.dumps("åäö")
'"\\u00e5\\u00e4\\u00f6"'
>>> ujson.dumps("åäö", ensure_ascii=False)
'"åäö"'
```
#### escape_forward_slashes
Controls whether forward slashes (`/`) are escaped. Default is `True`:
```pycon
>>> ujson.dumps("http://esn.me")
'"http:\\/\\/esn.me"'
>>> ujson.dumps("http://esn.me", escape_forward_slashes=False)
'"http://esn.me"'
```
#### indent
Controls whether indentation ("pretty output") is enabled. Default is `0` (disabled):
```pycon
>>> ujson.dumps({"foo": "bar"})
'{"foo":"bar"}'
>>> print(ujson.dumps({"foo": "bar"}, indent=4))
{
"foo":"bar"
}
```
## Benchmarks
*UltraJSON* calls/sec compared to other popular JSON parsers with performance gain
specified below each.
### Test machine
Linux 5.0.0-1032-azure x86_64 #34-Ubuntu SMP Mon Feb 10 19:37:25 UTC 2020
### Versions
- CPython 3.8.2 (default, Feb 28 2020, 14:28:43) [GCC 7.4.0]
- nujson : 1.35.2
- orjson : 2.6.1
- simplejson: 3.17.0
- ujson : 2.0.2
| | ujson | nujson | orjson | simplejson | json |
|-------------------------------------------------------------------------------|-----------:|-----------:|-----------:|-----------:|-----------:|
| Array with 256 doubles | | | | | |
| encode | 22,082 | 4,282 | 76,975 | 5,328 | 5,436 |
| decode | 24,127 | 34,349 | 29,059 | 14,174 | 13,822 |
| Array with 256 UTF-8 strings | | | | | |
| encode | 3,557 | 2,528 | 24,300 | 3,061 | 2,068 |
| decode | 2,030 | 2,490 | 931 | 406 | 358 |
| Array with 256 strings | | | | | |
| encode | 39,041 | 31,769 | 76,403 | 16,615 | 16,910 |
| decode | 25,185 | 24,287 | 34,437 | 32,388 | 27,999 |
| Medium complex object | | | | | |
| encode | 10,382 | 11,427 | 32,995 | 3,959 | 5,275 |
| decode | 9,785 | 9,796 | 11,515 | 5,898 | 7,200 |
| Array with 256 True values | | | | | |
| encode | 114,341 | 101,039 | 344,256 | 62,382 | 72,872 |
| decode | 149,367 | 151,615 | 181,123 | 114,597 | 130,392 |
| Array with 256 dict{string, int} pairs | | | | | |
| encode | 13,715 | 14,420 | 51,942 | 3,271 | 6,584 |
| decode | 12,670 | 11,788 | 12,176 | 6,743 | 8,278 |
| Dict with 256 arrays with 256 dict{string, int} pairs | | | | | |
| encode | 50 | 54 | 216 | 10 | 23 |
| decode | 32 | 32 | 30 | 20 | 23 |
| Dict with 256 arrays with 256 dict{string, int} pairs, outputting sorted keys | | | | | |
| encode | 46 | 41 | | 8 | 24 |
| Complex object | | | | | |
| encode | 533 | 582 | | 408 | 431 |
| decode | 466 | 454 | | 154 | 164 |
## Build options
For those with particular needs, such as Linux distribution packagers, several
build options are provided in the form of environment variables.
### Debugging symbols
#### UJSON_BUILD_NO_STRIP
By default, debugging symbols are stripped on Linux platforms. Setting this
environment variable with a value of `1` or `True` disables this behavior.
### Using an external or system copy of the double-conversion library
These two environment variables are typically used together, something like:
```sh
export UJSON_BUILD_DC_INCLUDES='/usr/include/double-conversion'
export UJSON_BUILD_DC_LIBS='-ldouble-conversion'
```
Users planning to link against an external shared library should be aware of
the ABI-compatibility requirements this introduces when upgrading system
libraries or copying compiled wheels to other machines.
#### UJSON_BUILD_DC_INCLUDES
One or more directories, delimited by `os.pathsep` (same as the `PATH`
environment variable), in which to look for `double-conversion` header files;
the default is to use the bundled copy.
#### UJSON_BUILD_DC_LIBS
Compiler flags needed to link the `double-conversion` library; the default
is to use the bundled copy.
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