If you copy and paste from ChatGPT, is there a watermark?

No. Pasting ChatGPT output into a document, an email or an assignment does not carry a watermark with it, because there is no watermark in the text to begin with. What can travel across are ordinary Unicode characters you cannot see — and they prove nothing about who wrote the words.

What the paste actually carries

Two things ride along that people mistake for a mark.

The first is hidden characters. ChatGPT output sometimes contains a narrow no-break space, codepoint U+202F, sitting where a normal space should be. It looks identical to a space and it survives copy-paste. When researchers reported these in newer OpenAI models in April 2025, OpenAI said they were not a watermark but a quirk of large-scale reinforcement learning. They turn up inconsistently — some responses have them, plenty do not.

The second is formatting. Copy from the browser and you usually get rich text rather than plain: headings, bold, list structure, sometimes HTML residue that Word or Google Docs then re-interprets its own way. That is a styling problem, not a provenance one.

Why finding one proves nothing

A narrow no-break space is not evidence. It is ordinary typography, used in French punctuation, in scientific units, and by word processors, translation tools and typesetting software. Text that has never been near a model can contain it, and text straight out of ChatGPT often does not.

So it fails in both directions. Its presence does not show a machine wrote something, and its absence does not show a person did. Anyone accusing a student or a colleague on that basis is reading a typography quirk as a confession.

How to check what you pasted

Paste it into the hidden character checker. It shows every invisible codepoint in the text, where each one sits, and hands you a cleaned copy back. Useful for tidying text before it goes somewhere strict about encoding; useless for working out who wrote it.

For the question underneath this one — whether OpenAI marks its text at all, and what it does mark — the longer answer is here.