Cleanfeed (Usenet spam filter)

Cleanfeed is a content filtering system used primarily in the UK to block access to online child sexual abuse material (CSAM). It was developed by the Internet Watch Foundation (IWF) in collaboration with internet service providers (ISPs) to help prevent the distribution of illegal content on Usenet and other online platforms. The system works by maintaining a list of URLs and file hashes associated with known abusive content.