msgspec¶
msgspec is a fast serialization and validation library, with builtin
support for JSON, MessagePack, YAML, and TOML. It features:
🚀 High performance encoders/decoders for common protocols. The JSON and
MessagePack implementations regularly benchmark as the
fastest options for Python.
🎉 Support for a wide variety of Python types. Additional types may
be supported through extensions.
🔍 Zero-cost schema validation using familiar Python type annotations.
In benchmarks msgspec decodes and validates JSON
faster than orjson can decode it alone.
✨ A speedy Struct type for representing structured data. If you already
use dataclasses or attrs, Structs should feel familiar. However,
they’re 5-60x faster for common operations.
All of this is included in a lightweight library with no required dependencies.
msgspec may be used for serialization alone, as a faster JSON or
MessagePack library. For the greatest benefit though, we recommend using
msgspec to handle the full serialization & validation workflow:
Define your message schemas using standard Python type annotations.
>>> import msgspec
>>> class User(msgspec.Struct):
... """A new type describing a User"""
... name: str
... groups: set[str] = set()
... email: str | None = None
Encode messages as JSON, or one of the many other supported protocols.
>>> alice = User("alice", groups={"admin", "engineering"})
>>> alice
User(name='alice', groups={"admin", "engineering"}, email=None)
>>> msg = msgspec.json.encode(alice)
>>> msg
b'{"name":"alice","groups":["admin","engineering"],"email":null}'
Decode messages back into Python objects, with optional schema validation.
>>> msgspec.json.decode(msg, type=User)
User(name='alice', groups={"admin", "engineering"}, email=None)
>>> msgspec.json.decode(b'{"name":"bob","groups":[123]}', type=User)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
msgspec.ValidationError: Expected `str`, got `int` - at `$.groups[0]`
msgspec is designed to be as performant as possible, while retaining some
of the nicities of validation libraries like pydantic. For supported types,
encoding/decoding a message with msgspec can be ~10-80x faster than
alternative libraries.
Highlights¶
msgspec is fast. It benchmarks as the fastest
serialization library for Python, outperforming all other JSON/MessagePack
libraries compared.
msgspec is friendly. Through use of Python’s type annotations,
messages are validated during deserialization in a
declarative way. msgspec also works well with other type-checking tooling
like mypy and pyright, providing excellent editor integration.
msgspec is flexible. It natively supports a wide range of
Python builtin types. Support for additional types can
also be added through extensions.
msgspec is lightweight. It has no required dependencies, and the
binary size is a fraction of that of comparable libraries.
msgspec is correct. The encoders/decoders implemented are strictly
compliant with their respective specifications, providing stronger guarantees
of compatibility with other systems.
