How to Correctly Download and Run OpenVoice Jupyter Notebooks on Windows

If you are getting errors like:

• NotJSONError
• “install json” message
• Jupyter refuses to open demo_part1.ipynb

You probably downloaded the HTML preview instead of the real notebook file. GitHub shows a nice rendered view of .ipynb files, but that page is NOT the actual notebook.

Correct Way to Download the Notebooks

1. Go to the main repo: https://github.com/myshell-ai/OpenVoice
2. Navigate to the notebook you want, e.g. demo_part1.ipynb
3. Click the Raw button (top-right of the file view)
4. Right-click → “Save as…” or press Ctrl+S
5. Make sure the file is saved with the exact name demo_part1.ipynb (not demo_part1.ipynb.html)
6. Repeat for demo_part2.ipynb and demo_part3.ipynb

A valid notebook file starts with { when opened in Notepad.

Full Working Windows Setup (Tested Dec 2025)

mkdir MelloTTs
cd MelloTTs

:: If you use pyenv-win
pyenv install 3.9.18
pyenv local 3.9.18

python -m venv mellovenv
mellovenv\Scripts\activate

git clone https://github.com/myshell-ai/OpenVoice.git
cd OpenVoice

pip install --upgrade pip
pip install torch torchvision torchaudio --index-url https://download.pytorch.org/whl/cpu
pip install -r requirements.txt
pip install jupyter jupyterlab ipykernel ipywidgets

python -m ipykernel install --user --name=mellovenv --display-name "Python (OpenVoice)"

:: Download models
python download_models.py   (or run the cell in the notebook)

jupyter notebook

Using Google Antigravity IDE

• Open the OpenVoice folder as a workspace in Antigravity
• Install the official “Jupyter” and “Python” extensions from the marketplace
• When opening any .ipynb, select the kernel Python (OpenVoice) or Python (mellovenv)

Result

All three demo notebooks now open and run without any JSON errors.

Feel free to copy-paste this entire guide if it helps you too! Tested & working on Windows 10 – December 2025

Happy voice cloning!