The Wayback Machine is an initiative of the Internet Archive, a 501(c)(3) non-profit, building a digital library of Internet sites and other cultural artifacts in digital form. Other projects include Open Library and archive-it.org.
Wayback Machine Availability API – Build your own tools.
WordPress Broken Link Checker – Banish broken links.
404 Handler for Webmasters – Help users get where they were going.
Content crawled via the Wayback Machine Live Proxy, a component of Internet Archive’s wayback machine project. The liveweb proxy captures the content of a web page in real time.
Detects dead pages, 404s, DNS failures & a range of other web breakdowns, offering to show archived versions via the Internet Archive’s Wayback Machine. In addition you can archive web pages, and see their most recent & first archives.
The Web is fragile, and littered with broken links. But as of today, Brave's desktop Browser users can heal many of those 404 "Page Not Found" links with one click.
— Internet Archive (@internetarchive) February 25, 2020