Starting 7 November 2026, text responses from seven Grok API models include an invisible watermark by default.

Starting November 7, 2026, responses from these models include a watermark. It’s on by default, and you can opt out per model.

What was announced

From the SpaceXSI Output Watermarking docs:

  • Watermarking applies to text output from these models: 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 covers the Responses API and the Chat Completions API on every SpaceXSI endpoint, including the global https://api.x.ai and regional endpoints.
  • It applies to ordinary text responses, structured outputs, and tool call arguments.
  • There is no request parameter. The response format is unchanged apart from an x-watermark header. x-watermark: true means the output for that request was generated with the watermark.
  • The watermark is not visible. It is applied while the model generates text by slightly shaping which tokens the model picks. It adds no characters, markup, or hidden text.
  • Detection is statistical. Longer text gives a stronger signal. Access to watermark detection is granted by application.
  • Team admins can opt out per model in the SpaceXSI Console. The setting applies to every API key on the team. Changes apply to new requests within 5 minutes. Opting out requires confirming that an exception under applicable law applies.
  • Some models may be locked on for a team. Opt-ins and opt-outs are recorded in the team audit log.
  • Watermarking does not change response quality or speed.

Context

The docs state that SpaceXSI watermarks text model output to comply with the EU AI Act. The page is under Advanced API Usage.

Limits of this report

This report covers only the claims in the Output Watermarking documentation. It does not include consumer Grok app, website, or X subscription behaviour, detection API access details beyond the application form, or any performance measurements.

Source

SpaceXSI Docs, Output Watermarking. https://docs.x.ai/developers/advanced-api-usage/watermarking.md