Google’s AI detection tool can now be tried by anyone

Google announced via a post on X (formerly Twitter) on Wednesday that SynthID is now available to anybody who wants to try it. The authentication system for AI-generated content embeds imperceptible watermarks into generated images, video, and text, enabling users to verify whether a piece of content was made by humans or machines.

“We’re open-sourcing our SynthID Text watermarking tool,” the company wrote. “Available freely to developers and businesses, it will help them identify their AI-generated content.”

SynthID debuted in 2023 as a means to watermark AI-generated images, audio, and video. It was initially integrated into Imagen, and the company subsequently announced its incorporation into the Gemini chatbot this past May at I/O 2024.

The system works by encoding tokens — those are the foundational chunks of data (be it a single character, word, or part of a phrase) that a generative AI uses to understand the prompt and predict the next word in its reply — with imperceptible watermarks during the text generation process. It does so, according to a DeepMind blog from May, by “introducing additional information in the token distribution at the point of generation by modulating the likelihood of tokens being generated.”

By comparing the model’s word choices along with its “adjusted probability scores” against the expected pattern of scores for watermarked and unwatermarked text, SynthID can detect whether an AI wrote that sentence.