SynthID is Google's system for watermarking AI-generated content, and its new public detector lets anyone check media for those marks. Here is how it works.

When a supported AI system creates content, SynthID embeds an imperceptible signal, a statistical pattern spread across the file rather than a visible logo or metadata tag.

The detector looks for that signal in uploaded images, video and audio. It does not judge whether a file "looks like AI"; it answers the narrower question of whether the watermark is present.

The marks are designed to survive common edits such as cropping, filters and compression, though heavy recompression can weaken them.

The tool checks content from Google and partners OpenAI, NVIDIA and Kakao, with Apple support expected later. It is available in English at synthid.com.

A missing watermark does not prove a file is authentic. Other generators use different watermarking systems or none at all.