W3 Catalog was an early web search engine, first released on September 2, 1993[1] by developer Oscar Nierstrasz at the University of Geneva.
[2] Unlike later search engines, like Aliweb, which attempt to index the web by crawling over the accessible content of web sites, W3 Catalog exploited the fact that many high-quality, manually maintained lists of web resources were already available.
W3 Catalog simply mirrored these pages, reformatted the contents into individual entries, and provided a Perl-based front-end to enable dynamic querying.
[3][4] At the time, CGI did not yet exist, so W3 Catalog was implemented as an extension to Tony Sander's Plexus web server, implemented in Perl.
[3] In February 2010, the domain name w3catalog.com was acquired,[5] and like the original index, each new website entry was manually reviewed before being added.