Google has implemented text watermarking in its Gemini app and web experience since 2024, while Claude models began marking text at the model level in August 2026. These watermarks are designed to be invisible and persist through copying and pasting.

The reverse-SynthID project reverse-engineers Google's SynthID watermarking system, which is embedded in images generated by Google Gemini. It utilizes signal processing and spectral analysis to identify the watermark's resolution-dependent carrier frequency structure and has developed a detector that achieves 90% accuracy in watermark identification.