Anubis Works

AI companies have started using a technique to evade rate limits where they will have a swarm of tens of thousands of scraper bots using unique residential IPs all accessing your site at once. It's very obvious in aggregate that you're being scraped, but when it's happening, it's very difficult to identify scraper vs. non-scraper traffic. Each time a page is scraped, it just looks like a new user from a residential IP is loading a given page.

Anubis helps combat this because even if the scrapers upgrade to running automated copies of full-featured web browsers that are capable of solving the challenges (which means it costs them a lot more to scrape than it currently does), their server costs would balloon even further because each time they load a page, it requires them to solve a new challenge. This means they use a ton of CPU and their throughput goes way down. Even if they solve a challenge, they can't share the cookie between bots because the IP address of the requestor is used as part of the challenge.

Tens of thousands of scraper bots for a single site? Is that really the case? I would have assumed that maybe 3-5 bots send lets say 20 requests per second in parallel to scrape. Sure, they might eventually start trying different ips and bots if their others are timing out but ultimately it's still the same end result: All they will realize is that they have to increase the timeout and use headless browsers to cache results and the entire protection is gone. But yes, I think for big bot farms it will be a somewhat annoying cost increase to do this. This should really be combined with the cloudflare captcha to make it even more effective.

Until someone writes the proof of work code for GPUs and it runs 100x faster and cheaper.

If you're sending 20 requests per second from one IP address you'll hit rate limits quickly, that's why they're using botnets to DDoS these websites.

Anubis et al. are also looking into alternative algorithms. There seems to be consensus that SHA-256 PoW is not appropriate

A lot of the worst offenders seem to be routing the traffic through a residential botnet, which means that the traffic really does come from a huge number of different origins. It's really janky and often the same resources are fetched multiple times.

Saving and re-using the JWT cookie isn't that helpful, as you can effectively rate limit using the cookie as identity, so to reach the same request rates you see now they'd still need to solve hundreds or thousands of challenges per domain.

There's lots of other ones but you want hashes that use lots of RAM, stuff like scrypt used to be the go-to but I am sure there are better, now.

A big part of the problem with these scraping operations is how poorly implemented they are. They can get a lot cheaper gains by simply cleaning up how they operate, to not redundantly fetch the same documents hundreds of times, and so on.

Regardless of how they solve the challenges, creating an incentive to be efficient is a victory in itself. GPUs aren't cheap either, especially not if you're renting them via a browser farm.