Google Opens Its SynthID AI-Content Detector to Everyone, Now Covering OpenAI, Nvidia and Kakao Images Too

Google made SynthID Detector -- the website that checks whether an image, video, or audio clip carries its invisible AI watermark -- free and open to anyone, worldwide, in English, on Oct. 7. The tool spent more than a year restricted to a waitlist of journalists, researchers, and media professionals after its May 2025 debut. Google DeepMind's Pushmeet Kohli announced the change, framing it as giving people "more context about the media you see online."

Having clear context about the content you encounter online helps you make informed decisions about what to trust.

The scale figures behind that table come entirely from Google's own count, and the different numbers measure different things:

The expansion is about coverage as much as access. Google's own blog post, per multiple outlets' reporting, says the detector can now read watermarks from four labs' models, not just its own: Gemini, Imagen, Lyria, and Veo, plus OpenAI, Nvidia, and Kakao. ElevenLabs separately supports SynthID on the audio side, and Apple is named as joining "soon," reportedly tied to SynthID support landing in iOS 27's own image tools. Since 2023, Google says it has applied SynthID to more than 180 billion images and videos -- up from the 10 billion-plus figure it cited at the tool's restricted May 2025 debut -- and roughly 240,000 years of audio, with Search, Chrome, and the Gemini app together handling over a million verification checks a day, up from 50 million total checks inside the Gemini app alone before May 2026. (Four partner labs covering most mainstream AI image and video tools is still a minority of all generative AI tools in active use -- there is no registry of how many models exist entirely outside any watermarking standard.)

The timing lines up with a separate watermarking move one day earlier: OpenAI began watermarking ChatGPT-generated text for users in the European Union on Oct. 6. That system works on different physics entirely -- a statistical pattern in word choice, not a signal in pixels or a waveform -- and SynthID Detector doesn't check for it at all. A reader handed a suspicious paragraph of text and a suspicious image is, as of this week, using two unrelated verification systems that happen to have launched a day apart.

That scale is also the tool's limit. SynthID Detector can only ever answer one question with confidence: whether a Google-ecosystem watermark is present. A clean result does not mean a file is human-made -- it means no SynthID signal was found, which is also exactly what an image from Midjourney, Grok, or any other non-partner model returns. The detector is structurally blind to content it was never built to read.

Coverage of the relaunch doesn't agree on one basic mechanic: whether checking a file requires an account. TheNextWeb, citing Engadget's hands-on report, says users must sign in with a Google, OpenAI, or Apple account. Cryptopolitan describes it as a free site anyone can use by uploading a file, with no login mentioned.

The announcement also plays out as a brand race, not just a safety one: SynthID, OpenAI's own verification page, and Meta's Content Seal are now three separate places a reader might check the same file, each run by the company whose models it was built to vouch for first. Whichever becomes the default habit effectively sets what "verified" means for most readers, regardless of which system is technically most accurate. The Oct. 7 rollout is also not yet universal in the most basic sense: it launched in English only, which is a narrower "public" than "available worldwide" implies on its own.

Google isn't the only lab whose detector has been tested against its own blind spots. A Reuters analysis published in July found that Meta's own AI-image detector -- built on a different watermark called Content Seal -- failed to flag 55% of AI-generated images once cropped to a third or half their original size, even though it caught all 40 uncropped originals. Meta said the watermark "may be lost if an image is heavily cropped." SynthID is a different watermark than Content Seal, but it faces the same physics: watermarks can reportedly be stripped from files in some cases, and a result only ever describes what survived to the point of checking.

The honest reading of Oct. 7 is a real expansion, not a solved problem: a detector that covered one company's models for a waitlist of testers now covers four companies' models for anyone with a browser. Whether that's enough to matter against content actually built to deceive -- the kind made specifically to avoid a watermarked model in the first place -- is a different question than the one SynthID Detector answers.