This one is even more frightening, as it's (as far as I know) a one-man show that could disappear at any time.

Yes, it could, but IA, which - up to now - looked more professional and reliable could, too. And, unexpectedly, that's what's happening now.

Maybe archive.ph will also surprise us, by being more resilient.

Anyway, it's an alternative, for now.

This is NOT anywhere near what the IA provides.

Yes, it's an alternative, not a copy. For example, it doesn't provide "emergency library" style borrowing, and maybe this missing feature is a pro, not a con.

It archives a much smaller part of the internet, it't not an IA replacement.

On the other hand, it's doing something similarly dubious with paywalled news articles in that it bypasses many news sites' paywalls and supposedly injects its own ads next to the content.

There are even many comment threads detailing their strategy to avoid legal takedown requests by serving content via an "anti-CDN" (i.e. always serving content from abroad whenever possible, to make legal actions more difficult).

I tried to hit archive.is, archive.ph and archive.org yesterday. They were all down, and archive.is seems to still be down.

Any chance you're using Cloudflare DNS (directly or via e.g. iCloud Private Relay)? The people (person?) running archive have a somewhat complicated history with them.

Not using Cloudflare DNS, I use my own recursive resolver. And by "archive", I assume you mean archive.org; archive.is and archive.ph are different people.

No, I meant .is, .today etc; archive.org does not do weird DNS things to my knowledge.