Install Lightning Thunder

Minimal dependencies

Follow these instructions to install PyTorch, nvFuser, and finally Thunder.

Install PyTorch and nvFuser with pip (command shown is for CUDA 12.1):

pip install --pre "nvfuser-cu121[torch]" --extra-index-url

cu121 can be replaced with cu118 depending on your CUDA version.

You’re all set with minimal dependencies, so you can follow Install Thunder.

Dependencies so far don’t include additional optimized kernels for execution like OpenAI Triton, cuDNN Fusion, or Apex. These are described in the following section, Optional dependencies.

Optional dependencies

Install Apex

Thunder can use NVIDIA’s Apex to accelerate some PyTorch operations. To install the Apex executor, first clone the Apex git repository and then execute the following command in the project’s root directory:

git clone
cd apex

pip install -v --no-cache-dir --no-build-isolation --config-settings "--build-option=--xentropy" ./

Install cuDNN

Thunder can use NVIDIA’s cuDNN Python frontend bindings to accelerate some PyTorch operations. cuDNN backend is a pure-lib python package which needs to downloaded separately.

pip install nvidia-cudnn-cu12 pip install nvidia-cudnn-frontend

You’re all set, now follow Install Thunder.

Install OpenAI Triton

Thunder can easily integrate OpenAI Triton kernels. You can install Triton using:

pip install triton

Install Thunder

You can now install Thunder:

pip install git+

Alternatively you can clone the Thunder repository and install locally:

git clone
cd lightning-thunder

pip install .