Skip to main content
Join the official 2020 Python Developers SurveyStart the survey!

For serializing Python objects to JSON (dicts) and back

Project description

Python versions Downloads PyPI version Code Coverage Scrutinizer Code Quality

  • Python 3.5+
  • Minimal effort to use!
  • No magic, just you, Python and jsons!
  • Human readible JSON without pollution!
  • Easily customizable and extendable!
  • Type hints for the win!

💗 this lib? Leave a ★ and tell your colleagues!

Example of a model to serialize:

>>> @dataclass
... class Person:
...    name: str
...    birthday: datetime
>>> p = Person('Guido van Rossum', birthday_guido)

Example of using jsons to serialize:

>>> out = jsons.dump(p)
>>> out
{'birthday': '1956-01-31T12:00:00Z', 'name': 'Guido van Rossum'}

Example of using jsons to deserialize:

>>> p2 = jsons.load(out, Person)
>>> p2
Person(name='Guido van Rossum', birthday=datetime.datetime(1956, 1, 31, 12, 0, tzinfo=datetime.timezone.utc))


pip install jsons


import jsons

some_instance = jsons.load(some_dict, SomeClass)  # Deserialization
some_dict = jsons.dump(some_instance)  # Serialization

In some cases, you have instances that contain other instances that need (de)serialization, for instance with lists or dicts. You can use the typing classes for this as is demonstrated below.

from typing import List, Tuple
import jsons

# For more complex deserialization with generic types, use the typing module
list_of_tuples = jsons.load(some_dict, List[Tuple[AClass, AnotherClass]])

(For more examples, see the FAQ)



Recent updates


  • Feature: Added warn_on_fail parameter to default_list_deserializer that allows to continue deserialization upon errors.
  • Feature: Added transform that can transform an object to an object of another type.
  • Feature: Added serializer and deserializer for pathlib.Path (thanks to alexmirrington).
  • Change: When loading a list fails, the error message now points to the failing index.
  • Bugfix: Fixed bug when dumping an object with an innerclass.


  • Bugfix: Fixed bug with postponed typehints (PEP-563).
  • Bugfix: Loading an invalid value targeting an optional did not raise.
  • Bugfix: Loading a dict did not properly pass key_transformers.
  • Bugfix: Loading a namedtuple did not properly use key_transformers.
  • Bugfix: Utilized __annotations__ in favor _field_types because of deprecation as of 3.8.


  • Feature: Added __version__ which can be imported from jsons
  • Bugfix: Dumping a tuple with ellipsis failed in strict mode.


  • Feature: Added a serializer for Union types.
  • Change: Exceptions are more clear upon deserialization failure (thanks to haluzpav).
  • Change: You can no longer announce a class with a custom name.
  • Bugfix: Fixed dumping optional attributes.
  • Bugfix: Dataclasses inheriting from JsonSerializable always dumped their attributes as if in strict mode.


  • Feature: Added strict parameter to dump to indicate that dumping a certain cls will ignore any extra data.
  • Feature: When using dump(obj, cls=x), x can now be any class (previously, only a class with __slots__).
  • Feature: Support for dumping Decimal (thanks to herdigiorgi).
  • Feature: Primitives are now cast if possible when dumping (e.g. dump(5, str)).
  • Feature: Dumping iterables with generic types (e.g. dump(obj, List[str])) will now dump with respect to that types (if strict)
  • Feature: The default_dict serializer now optionally accepts types: Optional[Dict[str, type]].
  • Change: Improved performance when dumping using strict=True (up to 4 times faster!).
  • Bugfix: set_validator with multiple types did not work.


  • Feature: Added a serializer/deserializer for time.
  • Feature: Added a serializer/deserializer for timezone.
  • Feature: Added a serializer/deserializer for timedelta.
  • Feature: Added a serializer/deserializer for date.
  • Bugfix: Dumping verbose did not store the types of dicts (Dict[K, V]).
  • Bugfix: Loading with List (no generic type) failed.
  • Bugfix: Loading with Dict (no generic type) failed.
  • Bugfix: Loading with Tuple (no generic type) failed.


Special thanks to the following contributors of code, discussions or suggestions:

alexmirrington tirkarthi, marksomething, herdigiorgi, jochembroekhoff, robinklaassen, ahmetkucuk, casparjespersen, cypreess, gastlich, jmolinski, haluzpav, finetuned89,

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for jsons, version 1.3.0
Filename, size File type Python version Upload date Hashes
Filename, size jsons-1.3.0-py3-none-any.whl (56.4 kB) File type Wheel Python version py3 Upload date Hashes View

Supported by

Pingdom Pingdom Monitoring Google Google Object Storage and Download Analytics Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page