jsonyx

jsonyx is a customizable JSON library for Python 3.8+. It is written in pure Python with an optional C extension for better performance and no dependencies. The documentation for jsonyx is available online at: https://jsonyx.readthedocs.io

Key Features

• JSON decoding, encoding and patching
• Pretty printing:

  {
      "foo": [1, 2, 3],
      "bar": {"a": 1, "b": 2, "c": 3}
  }

• Optionally supports these JSON deviations:

  {
      /* Block */ // and line comments
      "Decimal numbers": [1.0000000000000001, 1e400],
      "Duplicate keys": {"key": "value 1", "key": "value 2"},
      "Missing commas": [1 2 3],
      "NaN and infinity": [NaN, Infinity, -Infinity],
      "Surrogates": "\ud800",
      "Trailing comma": [0,],
      "Unquoted keys": {key: "value"}
  }

• Detailed error messages:

  Traceback (most recent call last):
    File "/Users/wannes/Downloads/broken.json", line 1, column 99-381
      ...sList": {"GlossEntry": {"ID": "SGM..."GML", "XML"]}, "GlossSee": "markup"
                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  jsonyx.JSONSyntaxError: Unterminated object
  

• Dedicated functions for reading and writing files and pretty printing

Benchmark (Feb 5, 2025)

We recommend to use orjson, msgspec or pysimdjson for performance critical applications:

encode	json	jsonyx	msgspec	orjson	fastest time
List of 256 booleans	4.49x	4.47x	1.00x	1.07x	1.95 μs
List of 256 ASCII strings	12.41x	14.20x	1.55x	1.00x	3.76 μs
List of 256 floats	23.03x	23.68x	1.31x	1.00x	8.08 μs
List of 256 dicts with 1 int	11.08x	13.61x	1.33x	1.00x	7.86 μs
Medium complex object	10.29x	11.47x	1.14x	1.00x	13.71 μs
List of 256 strings	22.45x	14.65x	2.15x	1.00x	14.31 μs
Complex object	7.11x	5.47x	1.00x	DNF1	212.52 μs
Dict with 256 lists of 256 dicts with 1 int	9.32x	11.44x	1.31x	1.00x	2359.82 μs

decode	json	jsonyx	msgspec	orjson	simdjson	fastest time
List of 256 booleans	4.64x	7.19x	2.99x	1.40x	1.00x	1.42 μs
List of 256 ASCII strings	7.61x	12.30x	5.04x	4.66x	1.00x	2.87 μs
List of 256 floats	11.04x	12.00x	2.18x	1.64x	1.00x	6.23 μs
List of 256 dicts with 1 int	12.14x	15.93x	6.82x	5.02x	1.00x	6.22 μs
Medium complex object	12.53x	19.08x	5.24x	4.46x	1.00x	7.72 μs
List of 256 strings	5.37x	4.11x	9.40x	7.26x	1.00x	17.52 μs
Complex object	9.21x	8.66x	8.91x	7.95x	1.00x	130.93 μs
Dict with 256 lists of 256 dicts with 1 int	18.00x	22.32x	12.38x	10.84x	1.00x	1622.21 μs

Warning

The Python version of jsonyx is up to 36.25x slower, so make sure you have a C compiler installed on Windows.

Footnotes

1. failed due to recursion error ↩