Python 3.13 Release November 2025 〈UHD〉

def main(): print(f"Python sys.version") print(f"JIT enabled: sys.flags.jit_enabled")

However, it hasn't been a free lunch. The migration required extension authors to audit their C code for thread safety strictly. While the "pure Python" experience is seamless, early adopters in late 2024 faced a fragmented ecosystem. By late 2025, that fragmentation has largely healed. If you are doing high-performance data science or web serving, the free-threaded build is the reason to upgrade. python 3.13 release november 2025