winloop
Windows version of uvloop
Decision gist · record as of 2026-08-14
Yes, if you run asyncio applications on Windows and need better I/O performance. The package is actively maintained, has no known vulnerabilities, and offers pre-built wheels for most Python versions. Install friction is moderate (requires build tools if compiling, but wheels are available). The MIT License is permissive. Main caveat: verify that your specific asyncio framework or libraries work correctly with the API changes Winloop introduces.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Visual C++ build tools to compile from source on Windows.
- Pre-built wheels are available for Python 3.8–3.14 on Windows x64 and ARM64, so pip install typically works without compilation.
- Medium install friction: compiled extension requiring Visual C++ build tools on Windows.
License · maintenance · safety
MIT License (permissive) — Licensed under MIT License with permissive treatment. No restrictions on commercial use, modification, or distribution; suitable for proprietary projects.
last release 2026-04-27 (109 days) · last repo commit 2026-08-10 · 231 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 158,891 downloads/mo, #10,711 on PyPI
Alternatives
Verify before relying
pip install winloop
import asyncio
import winloop
winloop.install()
# Now asyncio uses the winloop event loop
loop = asyncio.get_event_loop()- Actual performance improvement magnitude compared to standard Windows asyncio policies in real-world applications.
- Compatibility with all asyncio-based frameworks given the API changes mentioned in the description.
- Whether SSL problem resolution on Python 3.9 Windows is confirmed across current Python versions.
What it is and what it does
Winloop is a Windows port of uvloop, the high-performance asyncio event loop implementation. It replaces Python's standard Windows asyncio event loops with a libuv-based alternative designed to handle network I/O more efficiently. The package is maintained as an active fork because uvloop itself does not support Windows; Winloop removes Windows-incompatible features like forking and adapts subprocess handling to work within Windows constraints.
The library is intended for developers running asyncio applications on Windows who need better performance than the standard library provides. It requires calling `winloop.install()` to activate the custom event loop policy. Pre-built wheels are available for modern Python versions on Windows, though building from source requires Visual C++ build tools and Cython.
Use it for
- Accelerate web servers on Windows by replacing the default asyncio event loop.
- Improve TCP connection handling performance in Windows-based async networking applications.
- Work around SSL issues reported with Python 3.9 Windows asyncio event loop policies.
- Develop high-throughput async I/O applications on Windows without porting to Linux.
- Benchmark asyncio application performance improvements by swapping event loop implementations.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes, if you run asyncio applications on Windows and need better I/O performance.
The package is actively maintained, has no known vulnerabilities, and offers pre-built wheels for most Python versions. Install friction is moderate (requires build tools if compiling, but wheels are available). The MIT License is permissive. Main caveat: verify that your specific asyncio framework or libraries work correctly with the API changes Winloop introduces.
Install
winloop on PyPI
Before you install
Medium install friction: compiled extension requiring Visual C++ build tools on Windows. Active maintenance with recent commits and no known vulnerabilities. Supports Python 3.8 through 3.14 with pre-built wheels for Windows x64 and ARM64.
Requires Visual C++ build tools to compile from source on Windows. Pre-built wheels are available for Python 3.8–3.14 on Windows x64 and ARM64, so pip install typically works without compilation.
License in practice
Licensed under MIT License with permissive treatment. No restrictions on commercial use, modification, or distribution; suitable for proprietary projects.
Quickstart
pip install winloop
import asyncio
import winloop
winloop.install()
# Now asyncio uses the winloop event loop
loop = asyncio.get_event_loop()Verify before relying
- Actual performance improvement magnitude compared to standard Windows asyncio policies in real-world applications.
- Compatibility with all asyncio-based frameworks given the API changes mentioned in the description.
- Whether SSL problem resolution on Python 3.9 Windows is confirmed across current Python versions.
Package facts
| License | MIT License permissive |
| Python support | Supports the current Python release >=3.8.0 |
| Install friction | Medium. Platform-specific wheel |
| Runtime dependencies | None |
| Maintenance | Actively maintained 109 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 158,891 / month, #10,711 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableFramework :: AsyncIOIntended Audience :: DevelopersLicense :: OSI Approved :: Apache Software LicenseLicense :: OSI Approved :: MIT LicenseOperating System :: MacOS :: MacOS XOperating System :: Microsoft :: WindowsOperating System :: POSIXProgramming Language :: Python :: 3 :: OnlyProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9Programming Language :: Python :: Implementation :: CPythonTopic :: System :: Networking |
Evidence: winloop-0.6.3-cp310-cp310-win_amd64.whl; winloop-0.6.3-cp310-cp310-win_arm64.whl; winloop-0.6.3-cp311-cp311-win_amd64.whl; winloop-0.6.3-cp311-cp311-win_arm64.whl; winloop-0.6.3-cp312-cp312-win_amd64.whl; winloop-0.6.3-cp312-cp312-win_arm64.whl; winloop-0.6.3-cp313-cp313-win_amd64.whl; winloop-0.6.3-cp313-cp313-win_arm64.whl; winloop-0.6.3-cp314-cp314t-win_amd64.whl; winloop-0.6.3-cp314-cp314t-win_arm64.whl; winloop-0.6.3-cp314-cp314-win_amd64.whl; winloop-0.6.3-cp314-cp314-win_arm64.whl; winloop-0.6.3-cp38-cp38-win_amd64.whl; winloop-0.6.3-cp39-cp39-win_amd64.whl; winloop-0.6.3-cp39-cp39-win_arm64.whl
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