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Data validation, serialization, deserialization & form rendering. 🔢
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TypeSystem is a comprehensive data validation library that gives you:

  • Data validation.
  • Object serialization & deserialization.
  • Form rendering.
  • Marshaling validators to/from JSON schema.
  • Tokenizing JSON or YAML to provide positional error messages.
  • 100% type annotated codebase.
  • 100% test coverage.
  • Zero hard dependencies.


Python 3.6+


$ pip3 install typesystem

If you'd like you use the form rendering you'll also want to install jinja2.

$ pip3 install jinja2

If you'd like you use the YAML tokenization you'll also want to install pyyaml.

$ pip3 install pyyaml


import typesystem

class Artist(typesystem.Schema):
    name = typesystem.String(max_length=100)

class Album(typesystem.Schema):
    title = typesystem.String(max_length=100)
    release_date = typesystem.Date()
    artist = typesystem.Reference(Artist)

album = Album.validate({
    "title": "Double Negative",
    "release_date": "2018-09-14",
    "artist": {"name": "Low"}

# Album(title='Double Negative',, 9, 14), artist=Artist(name='Low'))

#, 9, 14)

# '2018-09-14'

# {'title': 'Double Negative', 'release_date': '2018-09-14', 'artist': {'name': 'Low'}}


There are plenty of other great validation libraries for Python out there, including Marshmallow, Schematics, Voluptuous, and many others.

TypeSystem exists because I want a data validation library that offers first-class support for:

  • Rendering validation classes into HTML forms.
  • Marshaling to/from JSON Schema.
  • Obtaining positional errors within JSON or YAML documents.


TypeSystem is BSD licensed code. Designed & built in Brighton, England.

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