互联网有一个“支付要求”按钮长达29年，Cloudflare刚刚启用它

The HTTP status code 402 has been in existence since 1997, originally reserved in the HTTP/1.1 specification for 'future use.' For nearly three decades, it remained unused until recently when Cloudflare and Stack Overflow introduced a new application. This system, known as pay-per-crawl, allows AI crawlers to request pages from participating websites, with the server responding with an HTTP 402 status and a price header. The crawlers must either pay the specified fee or leave, with no room for negotiation. Cloudflare manages about one in five websites on the internet, making this initiative a significant infrastructure-level monetization of AI training data, implemented at the same scale as the crawlers themselves operate.