jsonschema-rs 0.19.0

A high-performance JSON Schema validator for Python

jsonschema-rs

A high-performance JSON Schema validator for Python.

import jsonschema_rs

validator = jsonschema_rs.JSONSchema({"minimum": 42})

# Boolean result
validator.is_valid(45)

# Raise a ValidationError
validator.validate(41)
# ValidationError: 41 is less than the minimum of 42
#
# Failed validating "minimum" in schema
#
# On instance:
#    41

# Iterate over all validation errors
for error in validator.iter_errors(40):
    print(f"Error: {error}")

Highlights

• 📚 Support for popular JSON Schema drafts
• 🌐 Remote reference fetching (network/file)
• 🔧 Custom format validators

Supported drafts

Compliance levels vary across drafts, with newer versions having some unimplemented keywords.

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You can check the current status on the Bowtie Report.

Limitations

• No support for arbitrary precision numbers

Installation

To install jsonschema-rs via pip run the following command:

pip install jsonschema-rs

Usage

If you have a schema as a JSON string, then you could use jsonschema_rs.JSONSchema.from_str to avoid parsing on the Python side:

validator = jsonschema_rs.JSONSchema.from_str('{"minimum": 42}')
...

You can specify a custom JSON Schema draft using the draft argument:

import jsonschema_rs

validator = jsonschema_rs.JSONSchema(
    {"minimum": 42}, 
    draft=jsonschema_rs.Draft7
)

JSON Schema allows for format validation through the format keyword. While jsonschema-rs provides built-in validators for standard formats, you can also define custom format validators for domain-specific string formats.

To implement a custom format validator:

1. Define a function that takes a str and returns a bool.
2. Pass it with the formats argument.

import jsonschema_rs

def is_currency(value):
    # The input value is always a string
    return len(value) == 3 and value.isascii()


validator = jsonschema_rs.JSONSchema(
    {"type": "string", "format": "currency"}, 
    formats={"currency": is_currency}
)
validator.is_valid("USD")  # True
validator.is_valid("invalid")  # False

Performance

jsonschema-rs is designed for high performance, outperforming other Python JSON Schema validators in most scenarios:

• Up to 30-390x faster than jsonschema for complex schemas and large instances
• Generally 2-5x faster than fastjsonschema on CPython
• Comparable or slightly slower performance for very small schemas

For detailed benchmarks, see our full performance comparison.

Python support

jsonschema-rs supports CPython 3.8, 3.9, 3.10, 3.11, and 3.12.

Support

If you have questions, need help, or want to suggest improvements, please use GitHub Discussions.

Sponsorship

If you find jsonschema-rs useful, please consider sponsoring its development.

Contributing

We welcome contributions! Here's how you can help:

• Share your use cases
• Implement missing keywords
• Fix failing test cases from the JSON Schema test suite

See CONTRIBUTING.md for more details.

License

Licensed under MIT License.