I'm skeptical of this since a good general purpose search engine is also a good rationalist-site search engine with the right prompt engineering. Using (and paying for) multiple search engines seems worse than just appending "rationalist" or "lesswrong" to the end of a query in a normal search engine.

Personally I also don't think limiting to rationalist sites in general in really that useful in general. I occasionally search for specific rationalist sites because I want to find an article I already know about, but I don't think I've ever wanted to a limit a more general query to rationalist sites.

I have never in my life paid for a search engine, even though I'm not at all happy with the results from Google or Bing, because I detest subscriptions and because I had the impression that there aren't any paid search engines good enough to blow those big ones out of the water. (That said, this impression might be mistaken.)

And as an individual I wouldn't pay for a search engine just limited to rationalist sites. That kind of thing would provide me a bit of utility, but certainly not enough to warrant a paid subscription (yuck).

Also, when I browse, I usually want to have exactly one search bar where I can enter any arbitrary queries and get a result, without having to use a separate search engine for specific queries. The only situation where I am delighted to use another search engine is geizhals.de, a German price comparison site which produces really neat tables for comparison shopping of electronics. And that's a case where the search provides obvious monetary value (via savings on purchases) and is nonetheless as free as anything else on the Internet (i.e. financed by ads and affiliate links etc.).

Overall, I can't imagine that there would be a sufficient market for such a search engine among the user base, so I figure your actual customers (or funders) would have to be those rationalist and EA sites or grantmakers themselves.

E.g. I really don't like the search function on LW^[1], to the point that I prefer to use third-party search engines like Google to search for LW stuff. But I don't know whether the LW team (and by extension the EA Forum team, who use the same software) also considers their search to be a problem, and if so, if they would be able and willing to pay for an improvement.

PS: If you're considering using AI to improve search, another idea which could improve discoverability would be to auto-tag the LW corpus. The tags seem like a good system, but asking authors and readers to manually tag posts just doesn't work.

1. ^{^}

   As an example, searching for "harry potter and the methods of rationality" displays 3 random users, then 9 supplementary posts, and only then lists the "The Methods of Rationality" sequence, which is book 1 of HPMOR. This is the default search order sorted by "Relevance". Sorting by karma makes the results even worse, e.g. the top result is now the preface to Rationality: AI to Zombies.

When I am looking for rationalist content and can't find it, using Metaphor (free) usually finds what I want (sometimes even without a rationalist-specific prompt. Could be the data it was trained on? In any case, it does what I want.)

Don't there already exist extensions for google that you can use to whitelist certain websites (parental locks and such)? I'd think you could just copy paste a list of rationalist blogs into something like that? This seems like what you are proposing to create, unless I misunderstand.

I would not pay for it. Some thoughts:

• I don't find myself having a need here. Doing what Brendan said with appending "rationalist" or "lesswrong" or some other DuckDuckGo-fu to my search queries usually works. Sometimes I find myself browsing through tag pages here on LW too. Other times I'll look at sites like Stanford Encyclopedia of Philosophy or Stack Exchange. And with the advent of LLMs, I find myself increasingly using Claude instead of web searches.
• I suspect pretty strongly that this isn't the case, but I might be failing to see the usefulness of a search engine limited to rationalist sites. I think concrete examples of when you think it would be useful would be helpful. Do any come to mind?
• One somewhat large consideration is that, when I search for something, I type the query into my URL bar and then hit enter. I have my browser (Firefox) configured to automatically search DuckDuckGo when I do that. I think most browsers do something similar by default. So for normal, quick searches, I think the trivial inconvenience is actually pretty important and the rationalist search engine would be something I'd try only if the first approach of using the URL bar didn't work.
• I'm not sure how common this is, but I at least feel like there's some sort of cognitive overhead in play. Yet another monthly bill. Yet another think in my bookmarks. Yet another thing to keep in the back of my mind. I suspect I'm in something like the 99th percentile in how minimalist I am, but I also suspect that these sorts of thing are non-trivial considerations for maybe 10-70% of others.
• Personally, I would like to spend less time browsing the web. Suppose that the rationalist search engine was an improvement. If so, I think it'd be some sort of "one step forward and two steps back". Two steps back because I'd like to do less of this semi-productive web browsing; one step forward because (in this hypothetical) it'd make the semi-productive web browsing more productive.

I'm assuming this would basically be like a wrapper that takes a search term, concatenates it with a bunch of google "site:site1 OR site:site2..." boolean terms, then displays the results. If so, then sure, I'd like to have such a string pre-formed, but I don't think it's something that valuable to me personally, or something I'd pay for. If not, I'd be curious to hear more about what you mean.

It would be nice to be able to form such a search for a set of sites of my choosing (text box, comma separated list, something like that), or a list of recommendations for sites I might want to include but not know about yet (checkboxes?). 

Maybe a way to sort or filter by level of technical rigor or mathematical ability assumed?

Maybe an explanation, for each site searched, why that site is included, and a sentence or two about what to expect from things found on that site?

I think creating such a thing is a few hours of work with https://programmablesearchengine.google.com/about/ . Generally, those Google-based custom search engine don't find much use.