How to remove Claude's HTML from a fic on AO3
By Claude Watermark Research · Updated
Claude's web interface wraps its response paragraphs in class names containing the word “claude”, and AO3's rich-text editor preserves them when you paste directly. To remove them from an existing work: open Edit, switch the editor to HTML mode, and delete any class attributes on your paragraph tags — or simpler, copy your text into a plain-text editor, copy it back, and re-paste. Plain text carries no HTML at all, so nothing survives.
The quickest fix
Open your work, click Edit. Select all of the chapter text and copy it. Paste it into any plain-text surface — Notepad, TextEdit in plain-text mode, a code editor, even your browser's address bar in a pinch. Copy it back out and paste it over the original.
Plain-text surfaces discard formatting entirely, and the class attributes go with it. You will need to redo italics and bold, which is the trade-off.
The precise fix, if you have a lot of formatting
In AO3's editor there is an HTML toggle. Switch to it and you will see your work as markup. Look for class attributes on paragraph tags — anything of the form class="…claude…". Delete the whole attribute, leaving the tag itself intact.
This preserves your italics, links and paragraph breaks while removing only the identifying attribute. If your chapter is long, paste the HTML into our checker first: it strips exactly those attributes and leaves everything else alone, so you can paste the result straight back.
How to avoid it next time
The artifact only appears when you paste from the Claude interface directly into a rich-text editor. Any intermediate step removes it. Drafting in a document editor, or pasting through plain text once, is enough.
It is worth knowing this is not a watermark and not a detector. It is leftover markup from one specific web interface, and it says nothing about how much of the writing is yours.
Questions
- Will editing the work remove the flag for readers who already saw it?
- Yes. The skin evaluates the HTML as the page loads, so once the attribute is gone the banner stops appearing for everyone.
- Does this apply to ChatGPT or Gemini too?
- The specific class name is Claude's, but every chat interface leaves some markup. Other providers use different attribute names, and our checker looks for those too.
Check your own text. Free, unlimited, no account, and it runs in your browser so nothing is uploaded.
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