Clone the repository:
git clone https://github.com/zotero/reader --recursive
With Node 18+, run the following:
NODE_OPTIONS=--openssl-legacy-provider npm i
NODE_OPTIONS=--openssl-legacy-provider npm run build
This will produce dev, web and zotero builds in the build/ directory.
Run npm start and open http://localhost:3000/dev/reader.html.