I'm part of a team working on free-threaded support in Python ecosystem packages at Quansight Labs. See https://py-free-threading.github.io for more about our work.

This repo came up today on the aiohttp issue about free-threaded support: aio-libs/aiohttp#8796 (comment).

If I use our fork of CFFI to build, I can build pycares and run the tests. There's one failure:

FAILED tests/test_all.py::DNSTest::test_query_txt_chunked - AssertionError: 'v=spf1 A MX  ~all' != 'v=spf1 A MX include:emailcampaigns.net include:spf.dy[99 chars]~all'

That said, it doesn't look like there's any multithreaded test coverage either, so there might be dragons if you try to use pycares with threads under free-threading.