Python 3.15.0 released October 9, 2026 with 5,643 commits from 1,012 contributors.
Highlights: PEP 686 UTF-8 default encoding; PEP 810 lazy imports; PEP 814 frozendict; PEP 661 sentinel; PEP 829 package startup config; upgraded experimental JIT (7–8% geometric mean on x86-64 Linux, 11–12% on AArch64 macOS vs tail-calling interpreter); Windows 64-bit binaries use tail-calling interpreter; official macOS binaries install free-threading support by default.
Release notes warn of a known macOS 27.0 tkinter/IDLE hang issue.