Which Claude models are watermarked?
None of them, as of today. Anthropic marks models launched on or after 2 August 2026, and every shipped model predates that. Anthropic says earlier models are “in progress” under a transition period, so this page is dated.
Last checked 2026-08-11.
| Model | Launched | Watermarked |
|---|---|---|
| Claude Opus 5 | May 2026 | No |
| Claude Sonnet 5 | 2026, before 2 August | No |
| Claude Fable 5 | 2026, before 2 August | No |
| Claude Opus 4.8 | 2026, before 2 August | No |
| Claude Haiku 4.5 | 1 October 2025 | No |
The mark is not the thing catching people. No detector has been published, so nobody outside Anthropic can check it. What is verifiable today is the HTML Claude’s web interface leaves on your clipboard — paste your text in and see.
Check my text →
