Pug is a templating language, like HTML and JSX, but more terse. It was called Jade prior to 2016. Learn more about Pug.
This website is a frontend to the html2pug Node.js package, made for quick conversions through the browser.
The source code for this website, along with the code for the html2pug library, are both open source and available on Github. PRs for both are welcome.