The tells that mark text as AI-written

2026-09-22 · 6 min read

Most of what makes generated text recognisable is not the ideas. It is punctuation and invisible characters that no human types by hand, and they survive copy and paste into your document, your CMS and your email.

The typographic tells

Em dashes used mid-sentence where a comma or a colon would do. Almost nobody types one on a keyboard; models produce them constantly.
Curly quotation marks and apostrophes mixed into text that otherwise uses straight ones, which is what happens when generated text lands in a document written by a person.
Non-breaking spaces and narrow no-break spaces, which look like ordinary spaces and break search, line wrapping and diffing.
Zero-width characters that are entirely invisible and still present in the file.

The invisible ones matter most, because you cannot proofread what you cannot see. They show up later as a failed string match or a word that will not line-break.

The phrasing tells

Separate from punctuation, there is a house style: openings that announce what the text is about to do, closings that summarise what was just said, and hedging adverbs attached to claims that do not need them. None of these is wrong in isolation. Together and repeatedly, they read as filler, and a reader notices the rhythm before they notice any individual sentence.

What to strip and what to keep

Normalising punctuation and removing invisible characters is safe and mechanical: it changes how the text is encoded, not what it says. Rewriting stock phrasing is editorial and nobody can do it for you, but it is much easier once the mechanical noise is gone and you are reading sentences rather than artefacts.

Doing it without pasting into a stranger's server

Text you are cleaning is usually a draft: an unpublished article, a client email, a cover letter, internal documentation. Every tool here runs in your browser tab, so the draft stays on your machine. Load the page, disconnect from the internet, and the cleaning still works.

Frequently asked questions

Does removing em dashes change my meaning?

No. Replacing an em dash with a comma or a colon changes punctuation, not content. Read the result once, because occasionally a dash was carrying a genuine pause.

What are zero-width characters and why do they matter?

They are invisible characters that occupy no space. They break search, string comparison and line wrapping, and you cannot spot them by proofreading.

Is my text uploaded?

No. Everything runs in your browser tab, which you can verify by going offline once the page has loaded.