Legend:

• (G) — uses Google data
• (I) — uses Inktomi data
• (T) — uses Teoma data
• (*) — with clustering option
• (#) — with thumbnails of listed pages

Major search engines and directories:

Regular search engines and their databases:

• A9 (G)
• Alexa (G#) — with click-based web site ranking
• Alltheweb
• Altavista
• Ask / Ask Jeeves (T)
• Eurekster
• Fast
• Gigablast
• Go
• Google (G) — currently the largest and – on average – the most popular search engine… uses the Page Rank score system to judge every listed page's popularity.
• Hotbot
• Inktomi
• Lycos
• MSN (I) — see also…
• MSN Beta (Tech Preview).
• Northern Light
• Teoma (T)
• Yahoo (I) — uses the Web Rank score system to rate sites.

Meta search engines — drawing results from multiple databases:

• Clusty (*)
• Dogpile
• Ixquick
• Kartoo (*)
• Mamma
• Metacrawler
• Search.com
• Snap (*#) — click-based data and ranking?
• Vivisimo (*)

Web directories, most human edited (by volunteers):

• About
• DMOZ / Open Directory Project — lends its data to numerous clones and derivates, the most important being the…
• Google Directory
• Looksmart
• Thumbshots.org (#) — DMOZ clone.
• Wisenut
• Yahoo Directory
• Zeal — the non-commercial Looksmart branche.
• …more on the (free) directories pages…

Search tools, like search engines collections, guides, or specials:

• MrSapo and
• MyGo and
• TurboScout ;
  on these three sites, the same query can be run though multiple search engines successively.