SynthID Checker: How to Check an Image for Google's AI Watermark

The short answer

Only Google can read SynthID. Its detector is proprietary, so any website claiming to “detect SynthID” without an official integration is really running an ordinary AI classifier. We don't pretend otherwise: the tool below checks Content Credentials, metadata and AI patterns — useful evidence, but not the SynthID watermark itself.

What SynthID is

SynthID embeds a signal directly into the pixels (or audio samples, or text tokens) of content generated by Google's AI models. It is designed to survive common changes such as resizing, compression and moderate cropping, and it is invisible to people. Unlike metadata, it is not removed by a screenshot.

Where you can officially check for SynthID

Google's SynthID Detector— Google's own verification portal for images, video and audio.
The Gemini app — you can upload an image and ask whether it was made with Google AI.

Both only recognise content watermarked by Google and its announced partners. A “no watermark” answer does not mean the image is real — it may come from a generator that doesn't use SynthID at all.

SynthID vs. Content Credentials vs. AI detectors

	SynthID	Content Credentials (C2PA)	Pattern model
Where it lives	Inside the pixels	Signed record in the file	Nothing is embedded — the model inspects the image
Who can read it	Google only	Anyone, with open tools (we do it in your browser)	Whoever runs the model
Survives screenshots	Designed to	No — usually stripped	Works on screenshots, with lower accuracy
Covers which generators	Google and partners	Tools that sign their output	Any, as a probability

A practical order of checks

Run the image through the tool above. If it carries AI Content Credentials, you have your answer.
If it looks like it came from a Google model, confirm with Google's SynthID Detector or Gemini.
If neither gives a clear answer, weigh the pattern model's likelihood together with context: who sent it, where it first appeared, whether a reverse image search finds an original.

Why we don't claim to detect SynthID

Several sites rank for “SynthID detector” while running a generic classifier. If a tool tells you an image “has SynthID” without saying how it read the watermark, be sceptical. Our results always say which evidence they are based on. More on the method on the AI image detector page.