Marks its own text?What the provider has published
Can anyone outside verify it?Whether a public check exists for text
Google Gemini Gemini app and web
Not re-checked On 29 August 2026, Google said Gemini's text output carried SynthID-Text, and had done since 14 May 2024. This has not been re-checked in 49 days and may have changed.
deepmind.google/science/synthid/ai-generated-text/
Verified 29 August 2026 · review monthly
Not re-checked On 29 August 2026, Google's public checking covered images, video and audio, and text was not an accepted input. This has not been re-checked in 49 days and may have changed.
deepmind.google/models/synthid/
Verified 29 August 2026 · review monthly
Anthropic Claude All shipping models
Not re-checked On 29 August 2026, Anthropic said Claude models launched on or after 2 August 2026 support marking at launch, and that it was working to add marking to models released earlier. This has not been re-checked in 49 days and may have changed.
No Claude model has launched on or after that date. Opus 5 launched 24 July 2026, Sonnet 5 on 30 June. Anthropic publishes no per-model status.
support.claude.com … how-claude-marks-ai-generated-content
Verified 29 August 2026 · review monthly
Not re-checked On 29 August 2026, Anthropic said it would soon offer a watermark detection API and had not shipped one. This has not been re-checked in 49 days and may have changed.
anthropic.com/news/claude-text-watermark
Verified 29 August 2026 · review monthly
About 2 August 2026. That is the date the EU AI Act's Article 50 transparency obligations began to apply. Anthropic inherited it as a legal boundary rather than choosing it as a rollout date. It is not a date on which Claude output began carrying a mark, and no such date has been published. digital-strategy.ec.europa.eu … guidelines-ai-transparency-obligations · Verified 29 August 2026
OpenAI ChatGPT Text output
Not re-checked On 29 August 2026, OpenAI's provenance documentation covered images and audio only, and no text watermark was publicly documented. This has not been re-checked in 49 days and may have changed.
developers.openai.com/api/docs/guides/content-provenance
Verified 29 August 2026 · review monthly
Not re-checked On 29 August 2026, its provenance check endpoint accepted image and audio files, and text was not an accepted input. This has not been re-checked in 49 days and may have changed.
developers.openai.com/api/docs/guides/content-provenance
Verified 29 August 2026 · review monthly