Internet firm Cloudflare will start blocking artificial intelligence crawlers from accessing content without website owners' permission or compensation by default, in a move that could significantly impact AI developers' ability to train their models.

Starting Tuesday, every new web domain that signs up to Cloudflare will be asked if they want to allow AI crawlers, effectively giving them the ability to prevent bots from scraping data from their websites. The company will also allow publishers to charge AI crawlers for access using a new "pay per crawl" model.

Cloudflare is what's called a content delivery network, or CDN. It helps businesses deliver online content and applications faster by caching the data closer to end-users. They play a significant role in making sure people can access web content seamlessly every day.

Roughly 16% of global internet traffic goes directly through Cloudflare's CDN, the firm estimated in a 2023 report.

"AI crawlers have been scraping content without limits. Our goal is to put the power back in the hands of creators, while still helping AI companies innovate," said Matthew Prince, co-founder and CEO of Cloudflare, in a statement Tuesday.

AI crawlers are automated bots designed to extract large quantities of data from websites, databases and other sources of information to train large language models from the likes of OpenAI and Google.

Whereas the internet previously rewarded creators by directing users to original websites, according to Cloudflare, today AI crawlers are breaking that model by collecting text, articles and images to generate responses to queries in a way that users don't need to visit the original source.

This, the company adds, is depriving publishers of vital traffic and, in turn, revenue from online advertising.

Tuesday's move builds on a tool Cloudflare launched in September last year that gave publishers the ability to block AI crawlers with a single click. Now, the company is going a step further by making this the default for all websites it provides services for.

OpenAI says it declined to participate when Cloudflare previewed its plan to block AI crawlers by default on the grounds that the content delivery network is adding a middleman to the system.

The Microsoft-backed AI lab stressed its role as a pioneer of using robots.txt, a set of code that prevents automated scraping of web data, and said its crawlers respect publisher preferences.

"AI crawlers are typically seen as more invasive and selective when it comes to the data they consumer. They have been accused of overwhelming websites and significantly impacting user experience," Matthew Holman, a partner at U.K. law firm Cripps, told CNBC.

"If effective, the development would hinder AI chatbots' ability to harvest data for training and search purposes," he added. "This is likely to lead to a short term impact on AI model training and could, over the long term, affect the viability of models."

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