Sites you may not know but should.

DuckDuckGo (duckduckgo.com) — private search engine, no tracking/profiling
Marginalia Search (search.marginalia.nu) — indie search engine favoring small, text-heavy, non-commercial sites
Million Short (millionshort.com) — lets you strip out the top 100 to top 1,000,000 most popular sites from results
BASE (base-search.net) — searches academic repositories/papers, ~60% open access
Wayback Machine (web.archive.org) — Internet Archive’s tool for viewing historical snapshots of web pages
Right to be forgotten — not a site/tool, an EU legal process (handled via Google’s removal request form (support.google.com))
Yandex Images (yandex.com/images) — reverse image search, notably strong at facial matching
Shodan (shodan.io) — search engine for internet-connected devices

Here’s the list, same format:
Shodan (shodan.io) — search engine for internet-connected devices (webcams, servers, industrial systems)
Censys (censys.io) — scans the full IPv4 space, indexes SSL certs and server details
Intelligence X (intelx.io) — searchable archive of leaked breach data (emails, passwords, financial records)
Ahmia (ahmia.fi) — open-source search engine for Tor/dark web content that filters out abuse material; note it requires Tor Browser to actually open onion results