Ourshoppinglist is a Mobile-first Web application project. It was created by a team of two developers, using modern Javascript, ES6, React.js,Node.js DBOO database, Material UI, Arios......
Not sure if this would be on login screen or registration only. Maybe only requires on reg screen. Or could be a visible one on reg screen and an invisible on login.
See https://www.npmjs.com/package/react-google-recaptcha https://developers.google.com/recaptcha/docs/versions
or https://www.npmjs.com/package/reactjs-captcha