Python 3.13.0 (tags/v3.13.0:60403a5, Oct 7 2024, 09:38:07) [MSC v.1941 64 bit (AMD64)] on win32Run py -3.13t, and you’ll launch the free-threaded build:
Python 3.13.0 experimental free-threading build (tags/v3.13.0:60403a5, Oct 7 2024, 09:53:29) [MSC v.1941 64 bit (AMD64)] on win32
On Linux, the most convenient way to use multiple versions of Python generally is pyenv. A 3.13t or 3.13t-dev option for pyenv lets you install and select that build. (Ubuntu users can also work with the deadsnakes PPA to obtain these builds.)
When you use the free-threaded build, the GIL is included in the binary but disabled by default. If for some reason you want to re-enable the GIL in the free-threaded version, you can use the command-line option -X gil=1, or set the environment variable PYTHON_GIL to 1.