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Declare your AIndependence: block AI bots, scrapers and crawlers with a single click

07/03/2024

7 min read

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Declaring your AIndependence: block AI bots, scrapers and crawlers with a single click

To help preserve a safe Internet for content creators, we’ve just launched a brand new “easy button” to block all AI bots. It’s available for all customers, including those on our free tier.

The popularity of generative AI has made the demand for content used to train models or run inference on skyrocket, and, although some AI companies clearly identify their web scraping bots, not all AI companies are being transparent. Google reportedly paid $60 million a year to license Reddit’s user generated content, and most recently, Perplexity has been accused of impersonating legitimate visitors in order to scrape content from websites. The value of original content in bulk has never been higher.

Last year, Cloudflare announced the ability for customers to easily block AI bots that behave well. These bots follow robots.txt, and don’t use unlicensed content to train their models or run inference for RAG applications using website data. Even though these AI bots follow the rules, Cloudflare customers overwhelmingly opt to block them.

We hear clearly that customers don’t want AI bots visiting their websites, and especially those that do so dishonestly. To help, we’ve added a brand new one-click to block all AI bots. It’s available for all customers, including those on the free tier. To enable it, simply navigate to the Security > Bots section of the Cloudflare dashboard, and click the toggle labeled AI Scrapers and Crawlers.

This feature will automatically be updated over time as we see new fingerprints of offending bots we identify as widely scraping the web for model training. To ensure we have a comprehensive understanding of all AI crawler activity, we surveyed traffic across our network.

AI bot activity today

The graph below illustrates the most popular AI bots seen on Cloudflare’s network in terms of their request volume. We looked at common AI crawler user agents and aggregated the number of requests on our platform from these AI user agents over the last year:

When looking at the number of requests made to Cloudflare sites, we see that Bytespider, Amazonbot, ClaudeBot, and GPTBot are the top four AI crawlers. Operated by ByteDance, the Chinese company that owns TikTok, Bytespider is reportedly used to gather training data for its large language models (LLMs), including those that support its ChatGPT rival, Doubao. Amazonbot and ClaudeBot follow Bytespider in request volume. Amazonbot, reportedly used to index content for Alexa’s question-answering, sent the second-most number of requests and ClaudeBot, used to train the Claude chat bot, has recently increased in request volume.

Among the top AI bots that we see, Bytespider not only leads in terms of number of requests but also in both the extent of its Internet property crawling and the frequency with which it is blocked. Following closely is GPTBot, which ranks second in both crawling and being blocked. GPTBot, managed by OpenAI, collects training data for its LLMs, which underpin AI-driven products such as ChatGPT. In the table below, “Share of websites accessed” refers to the proportion of websites protected by Cloudflare that were accessed by the named AI bot.

AI Bot Share of Websites Accessed
Bytespider 40.40%
GPTBot 35.46%
ClaudeBot 11.17%
ImagesiftBot 8.75%
CCBot 2.14%
ChatGPT-User 1.84%
omgili 0.10%
Diffbot 0.08%
Claude-Web 0.04%
PerplexityBot 0.01%

While our analysis identified the most popular crawlers in terms of request volume and number of Internet properties accessed, many customers are likely not aware of the more popular AI crawlers actively crawling their sites. Our Radar team performed an analysis of the top robots.txt entries across the top 10,000 Internet domains to identify the most commonly actioned AI bots, then looked at how frequently we saw these bots on sites protected by Cloudflare.

In the graph below, which looks at disallowed crawlers for these sites, we see that customers most often reference GPTBot, CCBot, and Google in robots.txt, but do not specifically disallow popular AI crawlers like Bytespider and ClaudeBot.

With the Internet now flooded with these AI bots, we were curious to see how website operators have already responded. In June, AI bots accessed around 39% of the top one million Internet properties using Cloudflare, but only 2.98% of these properties took measures to block or challenge those requests. Moreover, the higher-ranked (more popular) an Internet property is, the more likely it is to be targeted by AI bots, and correspondingly, the more likely it is to block such requests.

Top N Internet properties by number of visitors seen by Cloudflare % accessed by AI bots % blocking AI bots
10 80.0% 40.0%
100 63.0% 16.0%
1,000 53.2% 8.8%
10,000 47.99% 8.92%
100,000 44.53% 6.36%
1,000,000 38.73% 2.98%

We see website operators completely block access to these AI crawlers using robots.txt. However, these blocks are reliant on the bot operator respecting robots.txt and adhering to RFC9309 (ensuring variations on user against all match the product token) to honestly identify who they are when they visit an Internet property, but user agents are trivial for bot operators to change.

How we find AI bots pretending to be real web browsers

Sadly, we’ve observed bot operators attempt to appear as though they are a real browser by using a spoofed user agent. We’ve monitored this activity over time, and we’re proud to say that our global machine learning model has always recognized this activity as a bot, even when operators lie about their user agent.

Take one example of a specific bot that others observed to be hiding their activity. We ran an analysis to see how our machine learning models scored traffic from this bot. In the diagram below, you can see that all bot scores are firmly below 30, indicating that our scoring thinks this activity is likely to be coming from a bot.

The diagram reflects scoring of the requests using our newest model, where “hotter” colors indicate more requests falling in that band, and “cooler” colors meaning fewer requests did. We can see the vast majority of requests fell into the bottom two bands, showing that Cloudflare’s model gave the offending bot a score of 9 or less. The user agent changes have no effect on the score, because this is the very first thing we expect bot operators to do.

Any customer with an existing WAF rule set to challenge visitors with a bot score below 30 (our recommendation) automatically blocked all of this AI bot traffic with no new action on their part. The same will be true for future AI bots that use similar techniques to hide their activity.

We leverage Cloudflare global signals to calculate our Bot Score, which for AI bots like the one above, reflects that we correctly identify and score them as a “likely bot.”

When bad actors attempt to crawl websites at scale, they generally use tools and frameworks that we are able to fingerprint. For every fingerprint we see, we use Cloudflare’s network, which sees over 57 million requests per second on average, to understand how much we should trust this fingerprint. To power our models, we compute global aggregates across many signals. Based on these signals, our models were able to appropriately flag traffic from evasive AI bots, like the example mentioned above, as bots.

The upshot of this globally aggregated data is that we can immediately detect new scraping tools and their behavior without needing to manually fingerprint the bot, ensuring that customers stay protected from the newest waves of bot activity.

If you have a tip on an AI bot that’s not behaving, we’d love to investigate. There are two options you can use to report misbehaving AI crawlers:

1. Enterprise Bot Management customers can submit a False Negative Feedback Loop report via Bot Analytics by simply selecting the segment of traffic where they noticed misbehavior:

2. We’ve also set up a reporting tool where any Cloudflare customer can submit reports of an AI bot scraping your website without permission.

We fear that some AI companies intent on circumventing rules to access content will persistently adapt to evade bot detection. We will continue to keep watch and add more bot blocks to our AI Scrapers and Crawlers rule and evolve our machine learning models to help keep the Internet a place where content creators can thrive and keep full control over which models their content is used to train or run inference on.

We protect entire corporate networks, help customers build Internet-scale applications efficiently, accelerate any website or Internet application, ward off DDoS attacks, keep hackers at bay, and can help you on your journey to Zero Trust.

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BotsBot ManagementAI BotsAIMachine LearningGenerative AI

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Adam Martinetti|@adamemcf
Reid Tatoris|@reidtatoris
Cloudflare|@cloudflare

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