`json`

Encode Python objects as JSON and decode JSON back into Python. Encoder and decoder are subclassable for custom types.

Source-of-record: Lib/json/, Modules/_json.c, json docs.

Functions

Function	Returns
`dump(obj, fp, , skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, cls=None, indent=None, separators=None, default=None, sort_keys=False, *kw)`	Write to file.
`dumps(obj, **kw)`	Return a `str`.
`load(fp, , cls=None, object_hook=None, parse_float=None, parse_int=None, parse_constant=None, object_pairs_hook=None, *kw)`	Read from file.
`loads(s, **kw)`	Parse a `str`/`bytes`.

Decoding produces dict, list, str, int or float, bool, None. json.loads accepts UTF-8, UTF-16, or UTF-32 bytes.

`JSONEncoder` parameter	Default	Effect
`skipkeys`	False	Drop non-string keys instead of raising.
`ensure_ascii`	True	Escape non-ASCII.
`check_circular`	True	Detect cycles.
`allow_nan`	True	Permit `nan` / `inf`.
`sort_keys`	False	Sort object keys.
`indent`	None	Pretty-print with this indent.
`separators`	None	Defaults: `(', ', ': ')` or `(',', ':')` with `indent`.
`default`	None	Fallback for unsupported types.

Override JSONEncoder.default(self, obj) to serialise new types.

`JSONDecoder` parameter	Effect
`object_hook(dict)`	Replace each object with a custom value.
`object_pairs_hook(list_of_pairs)`	Same; preserves order; mutually exclusive.
`parse_float(str)`	Parse number with a fraction.
`parse_int(str)`	Parse integer.
`parse_constant(str)`	Handle `Infinity`, `-Infinity`, `NaN`.
`strict`	When False, accept control chars in strings.

json.JSONDecodeError(msg, doc, pos) carries lineno, colno, pos, doc. Subclass of ValueError.

python -m json.tool reformats stdin or a file. Flags: --sort-keys, --indent, --no-ensure-ascii, --json-lines, --compact.

Area	State
`dumps` / `loads` byte-identical with CPython	Complete.
Encoder hooks (`default`, `cls`)	Complete.
Decoder hooks	Complete.
Streaming	Complete via `load`/`dump`.
`json.tool`	Complete.