# Setup > Colossal-AI currently only supports the Linux operating system and has not been tested on other OS such as Windows and macOS. > > Environment Requirement: PyTorch 1.10 ~ 1.12 (WIP higher version), Python >= 3.7, CUDA >= 11.0. If you encounter any problem about installation, you may want to raise an [issue](https://github.com/hpcaitech/ColossalAI/issues/new/choose) in this repository. ## Download From PyPI You can install Colossal-AI with ```shell pip install colossalai ``` If you want to build PyTorch extensions during installation, you can use the command below. Otherwise, the PyTorch extensions will be built during runtime. ```shell CUDA_EXT=1 pip install colossalai ``` ## Download From Source > The version of Colossal-AI will be in line with the main branch of the repository. Feel free to raise an issue if you encounter any problem. :) ```shell git clone https://github.com/hpcaitech/ColossalAI.git cd ColossalAI # install dependency pip install -r requirements/requirements.txt # install colossalai pip install . ``` If you don't want to install and enable CUDA kernel fusion (compulsory installation when using fused optimizer): ```shell CUDA_EXT=1 pip install . ```