DA
DaAwesomeP/tab-counter
A button badge that shows the number of tabs open in a window
tab-counter 
A button badge that shows the number of tabs open in a window. This addon was created as a WebExtension Replacement for Michael Kraft's Tab Counter. Tested for Firefox and Opera.
| Firefox |      |
| Opera |  |
| WebExtension |    |
| Chrome | Google charges a developer fee to enlist in the Chrome Web Store. Please use the Opera WebExtension download. |
Development
You will need NodeJS v7 or higher with the NPM v4 or higher.
# install dependencies
npm i
# build extension (makes ZIP archives in build/)
npm run build
# watch for changes and build dist/ (temporarily rename a manifest to load unpacked)
npm run watch
# check package.json and gulpfile.js for more commands