Google has opened SynthID Detector to the public worldwide, turning a tool that spent more than a year gated behind a waitlist for journalists, media professionals and researchers into open verification infrastructure. From today, anyone can visit synthid.com, upload an image, a video or an audio clip, and learn within seconds whether it carries an invisible AI watermark. The rollout is global but currently English-only, with no timetable announced for additional languages.
- Open access: The detector runs at synthid.com and covers images, video and audio. Google says the system and its built-in verification features in Search, the Gemini app and Chrome already handle more than 1 million requests a day.
- Partner footprint: SynthID now reads watermarks from Google’s own generation tools plus those of OpenAI, NVIDIA and Kakao. Apple is confirmed as the next partner, with support arriving soon, according to Google DeepMind.
- Operating scale: Google has watermarked over 180 billion images and videos since SynthID launched in 2023, along with 240,000 years of audio content — up sharply from the 100 billion media files reported in May.
How SynthID marks media, and how the detector reads it
SynthID does not inspect metadata or apply statistical filters to a file. It looks for an imperceptible watermark embedded at the moment of generation, distributed across pixels, video frames or audio waveforms rather than concentrated in a single spot. That design is precisely why the signal survives compression, cropping and moderate editing instead of vanishing at the first re-encode.
On upload, the detector reports whether the signal is present. For images it highlights the regions most likely to carry the mark; for audio it points to the time intervals where detection fired. Google’s supported models include Gemini, Imagen, Lyria and Veo, alongside generation features such as Nano Banana, Flow, ProducerAI and Vids. The site accepts a broad format list: JPG, PNG, BMP, WEBP, AVIF, HEIC, TIFF and GIF for images, MP4, MOV and WEBM for video, and WAV, MP3, OGG, FLAC, AAC and M4A for audio.
“As AI tools become better and easier to use, having clear context about the content you encounter online helps you make informed decisions about what to trust.”
The line comes from Pushmeet Kohli, VP of Science and Strategic Initiatives at Google DeepMind, who announced the expansion in a company blog post.
Why direct rivals keep signing up
Apple joining a standard built by a competitor in AI image generation looks counterintuitive until you factor in regulation. Europe’s AI Act obliges providers to identify the origin of synthetic content, and building a watermarking system with the necessary scale independently is both prohibitively expensive and slow. Adopting SynthID, which has been running for over two years, is simply the efficient path.
For Google the payoff is structural: whoever controls verification infrastructure shapes the wider ecosystem, as HTTPS and C2PA demonstrated before it. The move also speaks to a legitimacy gap that Stanford’s AI Index 2026 quantified — 73% of AI professionals expected a positive impact from the technology, against just 23% of the general public.
The competitive landscape remains fragmented. Microsoft and Meta run their own watermarking and verification standards, and a July investigation found Meta’s checker failed to flag its own cropped fakes. OpenAI, meanwhile, began watermarking ChatGPT text in the EU this week and operates a separate verification page that reads both SynthID and C2PA signals.
Attribution, not a universal AI detector
The limits deserve stating plainly. SynthID Detector identifies a watermark; it does not rule on whether content is AI-generated in general. Open-source models — hundreds of which are in active use — produce files that scan clean because nothing ever marked them. Google’s own site is explicit: “This is not a general AI detector. We can only detect media from the above companies, who have adopted SynthID technology.”
Results are also deliberately hedged. A positive reading states that media “was made or edited with Google AI,” meaning a lightly retouched photograph and one generated from scratch receive the same label, and adds that the file “may have been edited further since then.” The FAQ warns that no signal is completely robust and recommends collecting multiple data points before drawing a conclusion. Access details have varied too: early hands-on accounts suggest the site may ask users to sign in with a Google, OpenAI or Apple account, a step Google’s own announcement does not mention.
The strategic significance is that AI content marking finally has a piece of infrastructure combining real scale, universal access and heavyweight partners at the same time. The next test is whether distribution platforms go further than verification — YouTube could visibly flag SynthID-marked uploads from Veo and Lyria immediately, and the open question is when Meta and Microsoft calculate that the regulatory cost of staying outside the standard outweighs the cost of integrating. Google’s clear preference is to lead the standard before regulators mandate it. That negotiation is still open.