title: Web application authentication using React and Flask
body: <p>I am building a web application which uses React on the frontend and Flask on the backend (and deployed to Azure).
  I would like to implement user authentication/authorization.</p>
  
  <p>I understand how to implement this with pure Flask, but I am not sure how to achieve this when React is the frontend and Flask on the backend. 
  For example:</p>
  
  <ul>
  <li>Is still Flask handling this or is this done by React?</li>
  <li>If Flask authenticates the users, how do you send passwords in a secure way?</li>
  <li>etc etc etc</li>
  </ul>
  
  <p>Any advice/ link to resources is more than welcome.
  I am also open to suggestion on other ways to handle this.</p>