Search Engines:
DuckDuckGo
SearX
Google
Yahoo
Bing
DogPile
Yippy
StartPage
OneSearch (Verizon)
GiveWater (social impact)
Ekoru (climate change)
Ecosia (plants trees)
Baidu (chinese)
Excite
Lycos
Mojeek (UK)
WebCrawler (oldest)
Youdao (chinese)
metaGer (german)
Security Engines:
SearchCode (code)
GrayHatWar (AWS Buckets)
Hunter (email)
GhostProject (email)
wigle (WiFi networks)
FOFA (networks)
ZoomEye (pentesting)
Index Of
Insecam (open IP cams)
SearchCode (code)
NerdyData (tech being used)
Malc0de (malware code)
LeakedSource
Mamont's (open FTP)
BuiltWith (tech used on site)
Vigilante (breaches)
Specialized Engines:
binaryedge (tech)
Google Scholar
Google Images
Archive (old websites)
Shodan (IoT)
PublicWWW (source code)
WeboPedia (tech stuff)
Yandex (Russian)
CC Search (Copyright Free)
SwissCows (Swiss AI Search)
Gibiru (for patriots)
Wiki.com (search wikis)
BoardReader (message boards)
SlideShare (presentations)
Sci-Hub (research papers)
Deep Web-Dark Web:
Ahmia (web)
Ahmia (onion)
BTDigg (bit torrent)
DuckDuckGo (onion)
metaGer (onion)
Sci-Hub (onion)
Social Domain
Black Cloud (file share)