Howdy Stranger от Damn Interesting

From time to time it is useful for a domain to "forget" your browser, allowing you to use a site with a clean slate. Howdy Stranger accomplishes this by clearing out all of the data the website has deliberately saved to your browser (cookies, local storage, and session storage), then reloading the page anew. It's as if you are visiting the domain for the very first time.

Notes:
Clicking this button will log you out of all sites on the current domain (e.g., example.com)
The page is automatically refreshed after site data is cleared