# Claude watermarks text as of August 2026

Originally published at https://gifi.ai/blog/claude-watermarks-text

Anthropic now embeds a keyed word-choice mark in Claude models launched on or after 2 August 2026. There is no opt-out in the published story, and no public detector yet.

## What shipped

Anthropic published the method. Claude models launched on or after 2 August 2026 bias which ordinary word comes next, using a secret key and the words so far. Nothing is inserted. The sentence looks like English because it is English.

The mark sits at the model layer. The published write-up does not offer a header, a plan tier, or an off switch. Text from the Claude app, Claude Code, or the API is the same job if the model is in the marked set.

## What is still missing

A public detector. Anthropic has said one is coming. Until it lands, nobody outside Anthropic can verify the mark. A rewrite can change the words. It cannot certify their detector.

Older Claude models are still in transition. Do not treat every historical completion as marked.

## Where this sits on Gifi

The evergreen page is /claude-watermark. The mechanism explainer is /how-ai-text-watermarks-work. ChatGPT is a different story: it does not watermark text today.

## Primary sources

- [Anthropic on Claude text watermarking](https://www.anthropic.com/news/claude-text-watermark)