DeepSeek Watermark: What China's Labeling Law Actually Requires

DeepSeek's Open Platform Terms of Service, Section 3.7, put a labeling duty on developers who build on its API. Chinese law treats those developers as "network information service providers," and that status requires them to label AI-generated or synthesized content.

The same clause bans maliciously removing, altering, forging, or concealing a label once it's applied. That's an obligation on the people integrating the API, not proof that DeepSeek's own chat product carries anything embedded.

DeepSeek's consumer product does its own labeling, and its model and algorithm disclosure page names exactly three places it shows up:

• A reminder on the welcome page when a session starts
• A label appended to the end of generated text
• A notice at the bottom of the interface

All three state that the content is AI-generated and may be inaccurate. The disclosure page walks through that mechanism and stops: no invisible watermark, no statistical signal, no metadata scheme appears anywhere in it.

DeepSeek also issued a company announcement around September 1, 2025 confirming it had added content labeling under the same regulation.

China's Cyberspace Administration finalized the Measures for Labeling of AI-Generated Content, along with the mandatory national standard GB 45438-2025, on March 14, 2025. Both took effect September 1, 2025.

Among labeling regimes tracked across major jurisdictions, this is the most technically prescriptive one found anywhere. Instead of saying "disclose AI content," it defines two label types with named required fields:

• Explicit labeling: on-screen text, audio, or graphics a person can actually see or hear, with the Chinese-language tag "AI生成" as the standard example.
• Implicit labeling: machine-readable metadata embedded in the file itself, specifically the provider's name or code, a content reference number, and a watermark where technically feasible.

The measures cover five content types at once:

• Text
• Images
• Audio
• Video
• Virtual scenes

The obligation also doesn't stop at whoever generated the content. Platforms distributing it have to verify and enforce labeling on material their users upload.

That's a meaningfully wider net than most comparable rules, including the EU's Article 50, which mostly targets the entity building the AI system rather than every platform passing its output along.

The Phandroid report from around September 3, 2025 describes DeepSeek's labeling as pairing the visible label with an "implicit" hidden digital fingerprint that survives redistribution. It's more specific and more interesting than anything DeepSeek has published, which is exactly why it spread.

Neither DeepSeek's Open Platform Terms of Service nor its model and algorithm disclosure page says anything of the kind. Both describe the visible reminder and nothing else.

So the claim describes a general compliance category every covered platform in China has to satisfy. It isn't evidence of a DeepSeek-specific algorithm biasing token choices the way Google's SynthID does for Gemini.

Until DeepSeek publishes its own account of an embedding mechanism, or an independent test finds one, treat "DeepSeek has an invisible watermark" as community discussion rather than confirmed fact.

The first is images. DeepSeek has never published anything confirming a watermark, visible or invisible, in output from Janus-Pro, its MIT-licensed image generator.

That leaves DeepSeek's image line behind Google, OpenAI, Meta, and Amazon, each of which documents an invisible watermark in its own generated images.

The second is Europe. Every DeepSeek compliance document found addresses Chinese law only, and nothing from the company discusses the EU AI Act's Article 50 machine-readable marking requirement either way.

DeepSeek's API gets used well outside China, so for anyone serving EU users there's a live question here. Does labeling built for Chinese regulators do anything for a European one, or is this simply a gap nobody has closed?