Emotes Everywhere

Emotes Everywhere is a browser extension that lets you set custom emotes for the whole web. Pair unique codes with any image, and the extension will seamlessly insert your emotes inline on forums, social networks, chat clients... everywhere!

See source code and download/unpack from here.
Or, one-click install from:

Made for Google Chrome, Mozilla Firefox, and Microsoft Edge.
Version 0.3.2 tested with: Chrome 92, Firefox 91, Edge 92.