structtype

Fast data struct type with validation + JSON serialization for Python.

• High performance — 5-60x faster than dataclasses, attrs, or pydantic for common operations
• Schema validation — familiar Python type annotations, enforced at decode time
• No runtime dependencies — built on a monolithic C extension based on msgspec
• Rich type support — nested Structs, dataclasses, TypedDicts, enums, UUID, Decimal, datetime, and more
• JSON Schema generation — auto-generate JSON Schema 2020-12 / OpenAPI 3.1 specs

pip install structtype

uv add structtype

Requires Python ≥ 3.10.

from structtype import Struct

class User(Struct):
    name: str
    groups: set[str] = set()
    email: str | None = None

alice = User("alice", groups={"admin", "engineering"})

# Serialize to JSON
alice.struct_dump_json()
# b'{"name":"alice","groups":["admin","engineering"],"email":null}'

# Deserialize and validate
User.struct_validate_json(
    b'{"name":"alice","groups":["admin","engineering"],"email":null}'
)
# User(name='alice', groups={"admin", "engineering"}, email=None)

Full documentation is available at https://tds333.github.io/structtype/.

The library is in beta phase, interface and features may have breaking changes.

structtype is as fast as msgspec and about 3-5x faster than pydantic. See the benchmarks page for the full numbers.

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New BSD. See the License File. Parts of the core are based on the work of Jim Crist-Harif from msgspec.