Word Count Verified

Word Count shows how many words are on the page you're reading as a badge on its toolbar button. Click the button for the count and the site, right-click a page for "Count words on this page", or press Ctrl+Shift+U for a notification. It's the example extension from the Caspian developer guide — every part of it (content script, background, popup, options page, command, context menu, storage) is walked through at getcaspian.app/developers/extensions, so it doubles as a starting point for your own.