Yeah, what isn’t SEO spam—Search Engine Optimization spam, SEO marketing, keyword stuffing, Google keyword stuffing, backlink building, best backlinks, best backlinks for backlink building
It would be much harder to know what exists beyond "GBY" (Google, Bing, Yandex) and how it all works without the work of Rohan “Seirdy” Kumar. For three years, Kumar has been updating a heavily annotated list of search engines with their own indexes. It is 7,000 words, but only a portion of it deals with engines offering general indexing, in the English language. You can read Kumar's evaluation methodology for a better understanding of how he compared and assessed sites.
What stands out? Mojeek ("it's not bad… I'd live") and Stract ("a useful supplement to more major engines") are two of Kumar's favorites. Right Dao has "very fast, good results," in part because its crawler starts off from Wikipedia. Yep reaches farther out, showing results that link to and back from sites related to your query and also promises to share ad revenue with creators. All of them show promise, but you get the sense that they're a second car, or a third bicycle, rather than a primary transport.
There are far smaller-scoped engines in other sections of Kumar's post. If you're wondering where that one other search engine you've heard about is, it's probably in the "Semi-independent indexes" section, because it uses a GBY index when its own results are not strong enough. Here, you'll find cryptocurrency-friendly, controversy-courting-founder-having Brave, a few engines that either "resell" GBY results or stuff affiliate links into them, and "the most interesting entry," according to Kumar, Kagi.
Kagi requires an account and uses its own index, Teclis, in combination with Google, Bing, Yandex, Mojeek, and others, including, notably, Brave. Kagi's founder has strong opinions on the AI-based future of search and responding to harmful searches in ways that are not "scalable." How much of that does or does not bother you will vary, but it's worth noting that Kagi also suffers when the GBY triumvirate is restricted.
Before his company was able to block more of Microsoft's own tracking scripts, DuckDuckGo CEO and founder Gabriel Weinberg explained in a Reddit reply why firms like his weren't going the full DIY route:
“… [W]e source most of our traditional links and images privately from Bing … Really only two companies (Google and Microsoft) have a high-quality global web link index (because I believe it costs upwards of a billion dollars a year to do), and so literally every other global search engine needs to bootstrap with one or both of them to provide a mainstream search product. The same is true for maps btw -- only the biggest companies can similarly afford to put satellites up and send ground cars to take streetview pictures of every neighborhood.”
I wish I had saved one great comment on this. Can’t do it justice, but it was something about how since we know since we know everything will be used as training data, it's better to be posting in the open instead of inside a walled garden where one particular company will be doing its best to monetize it.