An authentication system comprises a browser extension and a password manager application. The browser extension can be configured for execution on a first user device. The browser extension can be configured to display a response code and receive a login credential from a server. The response code can comprise a unique session identifier identifying the browser extension and a user browsing session. The password manager application can be configured for execution on a second user device. The second user device can have a scanner configured to scan the response code. The password manager application can be configured to extract the unique session identifier, parse the unique session identifier into session identifier content, send a portion of the session identifier content to the server, receive an approval from a user of the second user device, and send a notification to the server.