Memento Project

Memento was a project of the United States National Digital Information Infrastructure and Preservation Program. It was funded with the aim of making Web-archived content more easily discoverable and accessible to the public. The project concluded on 5 September 2025.

WWW Official Site

Technical description

Memento is defined in RFC 7089 as an implementation of the time dimension of content negotiation. HTTP accomplishes negotiation of content via a variety of headers that allow clients and servers to find content that the user desires.

Request Header	Response Header	Dimension	Examples	Reference
Accept	Content-Type	content-type of the representation	text/html text/plain image/png	RFC 7231 RFC 2616
Accept-Language	Content-Language	language of the representation	en en-US cz	RFC 7231 RFC 2616
Accept-Encoding	Content-Encoding	medium, typically compression, that the content has been encoded with	compress gzip deflate	RFC 7231 RFC 2616
Accept-Charset	Content -Type	the character set used by the web page	iso-8859-5 unicode-1-1	RFC. 7231 RFC 2616
Accept-Datetime	Memento-Datetime	time of the representation	Fri, 15 Aug 2014 13:43:03 GMT	RFC 7089

The header provided by HTTP does not necessarily reflect when a particular version of a web page came into existence. Also, the header may not exist in some cases. To provide more information, the header has been introduced to indicate when a specific representation of a web page was observed on the web.

Usage

Copies of page can be found by simply navigating, in a web browser, to a link formatted, replacing urltoarchive with the full URL of the page desired.
JSON description of a Memento:http://timetravel.mementoweb.org/api/json/YYYY/urltoarchive, http://timetravel.mementoweb.org/api/json/YYYYMM/urltoarchive, http://timetravel.mementoweb.org/api/json/YYYYMMDD/urltoarchive, http://timetravel.mementoweb.org/api/json/YYYYMMDDHH/urltoarchive, http://timetravel.mementoweb.org/api/json/YYYYMMDDHHMM/urltoarchive
Or redirect to a Memento with a datetime that is close to a desired datetime:http://timetravel.mementoweb.org/memento/YYYY/urltoarchive, http://timetravel.mementoweb.org/memento/YYYYMM/urltoarchive, http://timetravel.mementoweb.org/memento/YYYYMMDD/urltoarchive, http://timetravel.mementoweb.org/memento/YYYYMMDDHH/urltoarchive, http://timetravel.mementoweb.org/memento/YYYYMMDDHHMM/urltoarchive