MDN Uptime bởi Nabendu

Goto any MDN website and it will show the time it takes for the site to come up.
MDN websites -
https://developer.mozilla.org
https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Examples

Or any other MDN website

This addon was created using React. Detail code at https://github.com/nabendu82/MDN-Uptime