Email validator flask_restx https://github.com/python-restx/flask-restx/blob/7ce0ef8056e66d81018e32dfe4b2dcc59dedfb83/flask_restx/inputs.py#L49 Django https://github.com/django/django/blob/eab67450b3ef4db99b9fed258063d88656daac4a/django/core/validators.py#L178C3-L178C3 jsonschema https://github.com/python-jsonschema/jsonschema/blob/edde408e009cfe181d650e5d15cd4f50184eef10/jsonschema/_format.py#L237 pydantic, wtforms https://pypi.org/project/email-validator/ marshmallow https://github.com/marshmallow-code/marshmallow/blob/27294efc374d9a073386bb6aba807e9b7eb525f6/src/marshmallow/validate.py#L230