ZeroMark.ai - clean AI text

Clean AI text where you write it. Right-click a selection on any page, or press Alt+Shift+Z, and zeromark strips invisible Unicode watermarks, model scaffolding, and assistant chatter in place. Nothing is uploaded: this add-on has no network code.

Language models leave marks on their output. Some are cosmetic, like curly quotes and em dashes. Some are structural, like a leftover reasoning block or a citation marker left in a copy-paste. And some are invisible: zero-width spaces, bidi controls, and characters from the Unicode Tags block, which can carry an entire tracking ID or URL through a paragraph without rendering a single pixel.

What it removes

• Invisible characters. Zero-width spaces and joiners, soft hyphens, bidi overrides, word joiners, and the whole U+E0000 Unicode Tags block, which is the channel most often used to hide text inside text.
• Model scaffolding. Reasoning and tool blocks, HTML comments, and leftover citation markers, contents included.
• Assistant chatter. The "Certainly! Here's the summary:" opener and the "I hope this helps! Let me know if you need anything else." sign-off, in English, Spanish or German.
• Typography. Curly quotes to straight, ellipsis and dash characters to plain ASCII, decorative bullets to hyphens.
• Whitespace. Non-breaking and ideographic spaces, line separators, repeated spaces, trailing spaces, and runs of blank lines. Code indentation is left alone.
• Emoji, if you ask. Off by default, because an emoji is content you can see and may well have meant.

How you use it

• Right-click a selection on any page and choose "Clean selected text".
• Right-click inside a text box with nothing selected to clean the whole field.
• Press Alt+Shift+Z instead, if you would rather not use the menu.
• Or click the toolbar button to open the sidebar and paste, when there is no field to work in. The sidebar stays open while you write and while you switch tabs, so you can compare against the page instead of losing your text to a popup that closes the moment you click away.

Text in an editable field is rewritten where it sits, and your undo history still works: press Ctrl+Z or Cmd+Z and your original text comes back exactly. A selection in ordinary page text is cleaned to your clipboard instead, because the page is not ours to rewrite.

It shows its work

Every clean reports how many edits it made, and the sidebar names each hidden character it found by codepoint, so you can audit the change rather than trust it. All six rule groups are yours to switch off.

Privacy

Your text never leaves your browser. There is no server, no account, no analytics, and no network code of any kind in this add-on. It requests no access to any website: the cleaner is injected into the current tab only after you invoke it, which is why the install prompt asks for no permission to read or change your data on any site, and states that no data is collected.

The only thing it stores is your six rule toggles and your writing language.

Emoji that mean something are protected: a family or skin-toned emoji keeps the zero-width joiners that hold its parts together, so it stays one glyph instead of collapsing into three, while a stray joiner used as a watermark is removed.

Requirements

Firefox 140 or newer, on desktop. Firefox for Android is not supported: the two main entry points are a context menu and a keyboard shortcut, and neither of them exists there.

Same engine as the free cleaner at zeromark.ai, so both give identical results.