Mozilla's Firefox may be lagging behind Chrome and Internet Explorer in market share, but it promises something those two browsers don't — no more 404s. Mozilla launched a new project on its Test Pilot platform this week that replaces missing web pages with archived entries for the site in question, giving users a glimpse at what would've been there if they'd searched before.

When presented with a missing page, Mozilla's No More 404s add-on will give Firefox users the option to visit an archived version, courtesy of the Internet Archive's Wayback Machine. Old or popular pages are likely to have snapshots available, but Mozilla's add-on won't work if there isn't a Wayback Machine entry for the page, if the site automatically redirects browsers to another page, or if it spits out another kind of error. No More 404s may be introduced to regular Firefox soon, but for now, it's only available on the browser's experimental Test Pilot platform.