This repo uses Python + Flask for the server and PNPM + Svelte + Vite for the client code. I'd also recommend using venv or your preferred virtual environment manager for python.
You'll also need to get API access from Splitwise: https://secure.splitwise.com/apps
First, copy cp app/secrets.json.example app/secrets.json
and update your secrets file with the API credentials from Splitwise.
Set up venv dependencies for the server
# If you're using venv
python -m venv venv
. ./venv/bin/activate
pip install -r requirements.txt
Install dependencies and build the client
cd app/client
pnpm install
pnpm build
Then, run the server from this directory with flask --app app run