FlashAttention Windows Wheel

Unofficial Windows-compatible wheel of flash-attention for Windows
Python 3.13-3.14 versions only.

Overview

This repository provides Windows-compatible wheels for FlashAttention-2 that are not officially distributed.
Pre-built version: flash_attn 2.9.2.post2 with Python 3.13-3.14 support.

!!Important!!

If you intend to use this alongside xformers, please note that versions v2.9.0 and later—which I developed myself—are not compatible. If you are using xformers, please use the latest official build, v2.8.4. I'll upload them.

Key Features

• ✅ Native Windows support (Python 3.12-3.14)
• ⚡ FlashAttention-2

Changelog

• 15.11.2025 Uploaded v2.8.3 based on PyTorch 2.9.1+cu130
• 12.02.2026 Uploaded v2.8.3 based on PyTorch 2.10.0+cu130
• 29.03.2026 Uploaded v2.8.3 based on PyTorch 2.11.0+cu130
• 14.05.2026 Uploaded v2.8.4 based on PyTorch 2.11.0+cu130
• 13.05.2026 Uploaded v2.9.0 based on PyTorch 2.11.0+cu130 — unofficial fork-only build (not the official FlashAttention release). Includes FA2 A-1/A-2 optimizations.
• 15.05.2026 Uploaded v2.9.0 based on PyTorch 2.12.0+cu132
• 23.05.2026 Uploaded v2.9.1 based on PyTorch 2.12.0+cu132 — unofficial fork-only build (not the official FlashAttention release). Includes FA2 A-1/A-2 optimizations.
• 03.07.2026 Uploaded v2.8.4 based on Pytorch 2.12.1+cu132 (Built on official-code for xformers-users)
• 11.07.2026 Uploaded v2.9.1 based on PyTorch 2.13.0+cu132 — unofficial fork-only build (not the official FlashAttention release). Includes FA2 A-1/A-2 optimizations.
• 12.07.2026 Uploaded v2.9.2 based on PyTorch 2.13.0+cu132 — unofficial fork-only build (not the official FlashAttention release.Blackwell=SM100,120,121.Legacy=SM80,89,90). Includes FA2 A-1/A-2 optimizations.
• 18.07.2026 Uploaded v2.8.4 based on Pytorch 2.13.0+cu132 (Built on official-code for xformers-users)
• 12.08.2026 Uploaded v2.9.2.post1 based on PyTorch 2.13.0+cu132 — unofficial fork-only build (not the official FlashAttention release.Blackwell=SM100,120,121.Legacy=SM80,89,90). Includes FA2 A-1/A-2 optimizations.
• 06.09.2026 Uploaded v2.9.2.post2 based on PyTorch 2.14.0+cu132 — unofficial fork-only build (not the official FlashAttention release.Blackwell=SM100,120,121.Legacy=SM80,89,90). Includes FA2 A-1/A-2 optimizations.
• 06.09.2026 Uploaded v2.8.4 based on Pytorch 2.14.0+cu132 (Built on official-code for xformers-users.Blackwell=SM100,120,121.Legacy=SM80,89,90)

About v2.9.x

v2.9.x is not an official FlashAttention release.
It is an independent fork build that continues FA2 kernel development while upstream focuses on FA3/F4.

• Optimization plan (GitHub): https://github.com/ussoewwin/flash-attention/blob/main/AI/FA2_BACKPORT_FROM_FA4_PLAN.md
• Kernel change notes (GitHub): https://github.com/ussoewwin/flash-attention/blob/main/md/FA2_CHANGES_v1.2.md
• About v2.9.1 A-1 / A-2 Refinements (GitHub): https://github.com/ussoewwin/flash-attention/blob/main/AI/A1_A2_REFINEMENTS_PLAN.md
• About v2.9.2 added 24 logics based on official repository (GitHub): https://github.com/ussoewwin/flash-attention/blob/main/md/split_align_kernels_explanation.md
• About v2.9.2.post1 A-1 / A-2 Refinements (GitHub): https://github.com/ussoewwin/flash-attention/blob/main/AI/A1_A2_REFINEMENTS_PLAN.md
• About v2.9.2.post2 (GitHub): https://github.com/ussoewwin/flash-attention/releases/tag/v1.8.1

Disclaimer

• No performance benchmarks have been run on this build.
• No multi-environment testing has been performed. (However, It's Working on my Stable Diffusuion A1111(※Customed), Forge Nunchaku(※Customed) and ComfyUI)
• Fork flash_attn 2.9.2.post2 — test of whether features work and can be used normally (log, GitHub): https://github.com/ussoewwin/flash-attention/blob/main/md/2.9.2.post2_COMPLETE_TEST_AND_VALIDATION_GUIDE.md
• This is an unofficial fork build. Use at your own risk.

※Unofficial built version!! It works correctly in my environment, but I am not sure that will work in yours.