This is not on in modern browsers. From the referenced help page (https://news.ycombinator.com/item?id=31170796 https://news.ycombinator.com/item?id=31170796):

This is not on in modern browsers. From the referenced help page (https://news.ycombinator.com/item?id=31170796 https://news.ycombinator.com/item?id=31170796): ** On modern browsers we accomplish this by adding a small piece of code to our page called Meta referrer. Some browsers (especially older ones) do not support this standard, however. For those browsers, and also in situations where meta referrer doesn't work, we send the request back to our servers to remove search terms. This redirect goes through r.duckduckgo.com. You can disable this privacy feature. To do that, go to the settings page, select Privacy, and change the option Redirect to Off. **