AI Watermark Detector
Check your text for AI watermarks
What is an AI watermark?
A hidden signal, not a visible mark
An AI watermark is an invisible signal hidden inside AI-generated text. You can't see it when you read, but it's woven into the writing so the model's maker can later tell the text came from their AI.
Added as the text is written
It works at the level of word choice. When an AI writes, it picks each word from a range of likely options. To watermark, the model nudges those picks using a secret pattern only its maker knows – subtle enough that quality doesn't drop, but consistent enough that the pattern can be recognized later.
Found by probability, not by reading it
AI watermarks leave a recognizable footprint in the writing itself. Smodin reads that footprint and tells you whether Claude or another model has stamped your text as AI-generated – clear and simple, before you publish.
Why AI watermarks matter
Since 2026, the major AI models watermark their output. Claude and Gemini now embed invisible watermarks into generated text by default, to comply with new EU AI Act rules. If you're publishing AI-assisted content, you want to know whether your text is watermarked before anyone else checks.
Check any AI model's output for watermarks
Detect Claude watermarks
Claude began embedding an invisible, model-level watermark rolling out from August 2, 2026 – on by default, with no opt-out. If Claude wrote your text after that date, assume it's watermarked. Smodin checks for it.
Detect ChatGPT watermarks
Here's what most tools get wrong: OpenAI has not deployed a watermark in ChatGPT. But that doesn't mean your text is in the clear – AI-generated content can still be identified as AI by the patterns in how it's written. Smodin gives you an honest read: no invented watermark, and a real check of whether your ChatGPT text is likely to be flagged as AI-generated.
Detect Gemini SynthID watermarks
Gemini marks its text with Google DeepMind's SynthID, an invisible watermark applied across Google's models. Smodin checks whether your text shows the signs.
How it works
Check any text for AI watermarks in three simple steps.
Paste your text
Drop in content from Claude, ChatGPT, Gemini, or any AI tool.
Run the watermark check
Smodin analyzes your text in seconds.
Get your result
See whether your text is likely watermarked – before you publish.
Why check your watermarks with Smodin
Accurate, not guesswork
Most tools get the basics wrong – claiming ChatGPT embeds a watermark it doesn't, or confusing one model's mark for another's. Smodin gives you a straight, correct read on what your text is actually carrying.
Honest results
If your text isn't watermarked, we tell you. No invented flags to push you toward an upsell – just a clear answer you can trust before you publish.
Private by default
Your text is never stored or shared. Paste, check, and it's gone – nothing kept on our side.
Always current
AI watermarking changed fast in 2026 – Claude, Gemini, EU AI Act rules. We keep the tool and our guidance up to date as models change.
One platform, more tools
Detection is one piece. Humanizer, Writer, Plagiarism Checker, and more live under the same login.
Detected a watermark? Here's your next step
Smodin's AI Watermark Detector tells you what your text is carrying. When you're ready to clean it up, the AI Humanizer rewrites AI-generated content into natural writing that reads as your own – with your meaning fully intact.
Write, detect, and polish – all in one platform
Ready to check for AI watermarks?
Run your text through Smodin's AI Watermark Detector and get a clear, honest result in seconds.