A Python (3.5+) lib for easily and deeply serializing Python objects to dicts or strings and for deserializing dicts or strings to Python objects using type hints.

Programming language: Python
License: MIT License
Tags: Serialization     JSON     Python    
Latest version: v1.1.1

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  • 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!

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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 __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.


  • Bugfix: Loading Dict[K, V] did not parse `K


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