Tutorial:

1. Install and open.

- After installing the extension. Click on the extension icon

- Click on the extension icon once you are on any website.

Quick access to Facebook Messenger by pressing the Go to Facebook Messenger button

When your friend or someone sends you a message from facebook messenger

You can read the message without showing a "seen" status. Note: the extension only works at https://www.facebook.com/messages

Enjoy the Unseen for Facebook Messenger