Python 3.13 alpha 4

It’s time for Python 3.13.0 alpha 4 (now with SPDX SBOM OMG!):

This is an early developer preview of Python 3.13

Major new features of the 3.13 series, compared to 3.12

Python 3.13 is still in development. This release, 3.13.0a4, is the fourth of six planned alpha releases.

Alpha releases are intended to make it easier to test the current state of new features and bug fixes and to test the release process.

During the alpha phase, features may be added up until the start of the beta phase (2024-05-07) and, if necessary, may be modified or deleted up until the release candidate phase (2024-07-30). Please keep in mind that this is a preview release and its use is not recommended for production environments.

Many new features for Python 3.13 are still being planned and written. Work continues apace on both the work to remove the Global Interpeter Lock, and to improve Python performance. The most notable changes so far:

(Hey, fellow core developer, if a feature you find important is missing from this list, let Thomas know.)

The next pre-release of Python 3.13 will be 3.13.0a5, currently scheduled for 2023-03-12.

More resources

Enjoy the new releases

Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organization contributions to the Python Software Foundation.

Regards from dusky Amsterdam,

Your release team,
Thomas Wouters @thomas
Ned Deily @nad
Steve Dower @steve.dower
Łukasz Langa @ambv


Just noting that alpha 4 won’t make it onto the Microsoft Store, as some of the free-threaded build changes caused the package to be broken. Tracking the fix here (but I’m away for the weekend, so it’ll be next week).

Shouldn’t really impact many people as the Store page isn’t searchable yet, though I occasionally share the direct link for unusually keen people.

For the even more unusually keen people, or those who just want to help test the build/release process, there are new Nuget packages up for free-threaded builds (which are not yet free-threaded… but hopefully soon), and a not very obvious option in the normal Windows installer. If you do try them, I’m very interested in anything that flat out fails to launch - once you can get to a normal prompt, it becomes a regular free-threaded bug, so don’t bother to tag me on it, but if you can’t get that far please file an issue and tag me.

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WASI build at Release CPython 3.13.0a4 w/ WASI SDK 20 · brettcannon/cpython-wasi-build · GitHub .

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CI images updated.