meta:static@1681811850
Failures in the following link (it doesn't know stuff after September 2021)
https://chat-gpt.org/chat
->
>>What type of captcha does 4chan use?
>As an AI language model, I cannot browse the internet, so I do not have access to the current state of the captcha system that 4chan uses. However, it is known that 4chan has used different types of captchas throughout its history. In the past, 4chan used the standard text-based captcha system, but it has also used image recognition captchas and math-based captchas. The website may continue to use a combination of different captcha systems to prevent spam and automated bots from flooding its forums.
>>What is the name of the captcha system that 4chan uses?
>The captcha system that 4chan uses is called reCAPTCHA.

Pretty sure 4chan never used math-based captchas. It never used a combination, only one at a time. I know that 4chan once used reCAPTCHA v2/v3, but I don't know exactly when that website quit using it. In 2021 it didn't use reCAPTCHA, I think. I know that that imageboard did not use reCAPTCHA in 2022 and 2023. It currently uses this captcha system which is either unnamed or maybe named "twister" based on some text in the webpage source code:
https://sys.4channel.org/captcha?framed=1&board=[board here, e.g. "mu" without quotes]&thread_id=[thread number here]