The only “other engine” that matters is really a thin paid SERP façade in front of a scraped Google result. In other words, Kagi pays for access to an API whose implementation is basically live scraping Google and throwing away the ads.

There are a few other indexes that Kagi’s aggregator mixes in (such as Bing Search) but those haven’t been contributing much in terms of meaningful results. The sheer size of Google’s index still dwarfs all the others, including Bing Search.

So yes, Kagi doesn’t scrape but they pay SERP providers who do.

They pay scraping sites for results, including SERP API. When I pointed this out, last time Kagi was discussed on Hacker News, an employee of Kagi said that they're trying to build their own internal index, but he didn't provide details.

Is Marginalia the only real competing search engine?