This is a QR CODE GENERATOR web app, created with React with Gatsby.
It's SEO ready, using Gatsby's Plugins. Also, it's built in with I18n plugin (English and Brazilian Portuguese included).
The web app uses Google API to generate the QR Codes, so you don't need a backend server for that.
It's responsive and fits very well in every device screen.
The code is easily extensible and follows React's best practices.