The short version
● Date — on by default from 7 November 2026
● Models — grok-4.7, 4.6, 4.5, 4.3 and three grok-4.20 variants
● Detection — the x-watermark response header
● Opt-out — team admin only, and written to the audit log
From 7 November, text from seven Grok models carries an invisible watermark by default. The covered list is grok-4.7, grok-4.6, grok-4.5, grok-4.3, grok-4.20-reasoning, grok-4.20-non-reasoning and grok-4.20-multi-agent. It applies to the Responses and Chat Completions APIs, covering ordinary text, structured outputs and tool call arguments, on every endpoint including regional ones.
Nothing changes in your code. There is no request parameter and the response format is unchanged apart from a new x-watermark header: a value of true means that output was watermarked, and anything else, or a missing header, means it was not. The watermark is applied during generation by slightly shaping which tokens the model selects, so it adds no characters, markup or hidden text. Detection is statistical and returns watermarked, not watermarked, or uncertain, with longer text giving a stronger signal. Access to the detection API is granted by application.
Opting out is a team-admin action in the Console under Model output watermarking. It applies to every API key on the team and takes effect for new requests within five minutes. It also requires confirming an exception under applicable law and accepting sole responsibility for any marking or disclosure requirement, and some models may be locked on for a team and cannot be turned off at all. Every opt-in and opt-out is written to the team audit log. The stated reason is the EU AI Act. For the current tier and pricing picture, see our Grok updates for November 2026.
More from 5 November
Full dated index: every AI release in November 2026.
Sources