If you’re writing a networked application, you’ll need some agreed upon
protocol that your clients and servers can use to communicate. JSON is a decent
choice here (though there are many other options). It’s ubiquitous, and Python
has many libraries for parsing it into builtin types (
However, servers don’t just parse JSON, they also need to do something with it.
msgspec goes above and beyond other Python JSON libraries to help with the
If a field is missing from a request or has the wrong type, you probably want to raise a nice error message rather than just throwing a 500 error.
msgspeclets you describe your schema via type annotations, and will efficiently validate messages against this schema while decoding.
What your application actually does! While builtin types like dicts are fine for writing application logic, they aren’t as ergonomic as custom classes (no attribute access, poor type checking, …).
msgspecsupports a wide variety of types, letting you decouple the objects your application logic uses from those that JSON natively supports.
Application needs change; you’ll want to make sure your clients/servers won’t break if the JSON schema evolves over time.
To handle this,
msgspecsupports “schema evolution”. Messages can be sent between clients with different schemas without error, allowing systems to evolve over time.
While there are other tools in this space,
msgspec should be an order
of magnitude faster than other options. We also hope that it’s
quick to learn and friendly to use, letting you focus less on serialization and
more on your application code.