For users in China and some other authoritarian counties where the Internet is heavily managed, surveyed, and censored by the government, “404 Not Found” may be one of the most common pages they’ve come across online. But they may no longer be frustrated to see such page coming up if they user Mozilla’s Firefox browser.
Earlier last week, Mozilla launched a new project on its Test Pilot platform that replaces missing web pages with archived entries for the site in question, giving Internet users a chance to get a glimpse of what would have been there if they’d searched before. For this function to be accessible, users will need to install the “No More 404s” add-on that allows the browser to visit an archived version of the searched website, courtesy of the Internet Archive’s Wayback Machine.
If there is indeed a snapshot for the site in question available, the browser will present it to the user the entry accordingly. This add-on may be introduced to regular Firefox soon, but for now, it’s only available on the browser’s experimental Test Pilot platform.
As of September 2015, around 3,000 websites were blocked in mainland China under the country’s policy of Internet censorship. If you want to get around some censorship in China, check our tutorial on how to access facebook in China.