SearX and Searxng are the most common options, but instances often get blocked by the engines they use. Users need to switch between instances quite often.

eTools.ch uses commercial APIs so it doesn't get blocked, but it might block you instead (very sensitive bot detection).

Dogpile is one of the older metasearch engines, but I think it only uses Bing- and Google-powered engines.

per other folks on thread, nearly impossible legally due to TOU/TOS or getting around those restrictions with rotating proxies, remote browsing + proxies, etc.

also part of why going with topic filter approach at Breeze -- so if you search all the web, we'll give you option to open others with indie indexes in new tab - say Mojeek or Yandex -- similar to what airline search engines do

if you switch to say code search, you can use ours or redirect to any one of say PublicWWW, Nerdy Data, or Builtwith

pretty much no other legal way to do it on the main

Search engines typically probihit this kind of usage via their TOS

SearX?