It is an Online QR Code Scanner from TheDoggyBrad that is easy to use.
It is free from any danger, tracking and advertisements unlike others.

You may access this QR Code Scanner here: https://thedoggybrad.github.io/qrscanner/

Using the official shortened link you may visit this at: https://cutt.ly/qr-scanner

The resource I use to built this: https://github.com/gokulkrishh/qrcodescan.in

1.) Mobile Browsers
-To install the app, just click the 3 dots (or similar on other browsers) then click Install App.

2.) Desktop Browsers
-To install the app, you may click the share button on the address bar then click the download button
or
-To install the app, click the 3 dots or similar then go to More Tools and click Create Shortcut. Make sure to tick the option "Open in new window" or similar.