humanflow

Invisible character detector

Finds Unicode characters that render as nothing but are really in your text — zero-width spaces, soft hyphens, non-breaking spaces and Cyrillic letters that look identical to Latin ones. Shows what each one is and gives you a cleaned copy.

Runs entirely in your browser — nothing is uploaded, and there is no account or limit.

Last reviewed 15 August 2026 · The HumanFlow team

What this actually finds

Two categories. The first is characters that render as nothing at all — a zero-width space, a byte-order mark, a soft hyphen. The second is characters that look exactly like ordinary letters but are not, such as the Cyrillic о in place of a Latin o. Both are present in the text and both are visible to any system comparing it.

The first kind usually arrives by accident. The second effectively does not, which is why they are reported separately above rather than lumped together as anomalies.

Why it matters if your work is questioned

An integrity flag for hidden characters is stronger evidence than a detection score, because it describes something checkable about the file rather than an inference about how the writing reads. If you have been asked about one, the honest explanation is usually the true one — text was pasted from somewhere that carried them — and knowing where they came from is a much better answer than not knowing.

The background is in our glossary entry on invisible characters, and the wider question of what a report is actually telling you is covered in originality report. If you are dealing with an accusation now, start with falsely accused of using AI.

Common questions

Where do invisible characters come from?
Almost always from copying. Web pages, PDFs, design tools, messaging apps and word processors all insert them for layout or encoding reasons, and they travel with the text when you paste. Finding some in your work is ordinary and is not evidence of anything by itself.
Why do plagiarism and integrity reports flag them?
Because they are trivial to detect. Unlike an AI writing score, a hidden character is an observable property of the file — it either is there or it is not, and no judgement about writing style is involved. That makes an integrity flag a different class of finding from a detection percentage.
Does removing them change my writing?
No. Every character this tool removes renders as nothing or as a space. The cleaned copy reads identically; it is the underlying bytes that differ. Space-like characters are replaced with an ordinary space rather than deleted, so words do not run together.
Should I add invisible characters to avoid text matching?
No, and we would advise against it whatever you think of the underlying score. Deliberately inserting them demonstrates intent in a way a percentage never does, which converts an arguable case into a straightforward one.
Are curly quotes and em dashes flagged?
No. They are visible, correct typography, and flagging them would teach people to strip punctuation out of their own writing. This tool covers characters that are invisible or that impersonate an ASCII character.

Need more than a utility?

HumanFlow rewrites AI drafts to read naturally and scores them for AI, with the signals behind the number — free up to 1,500 words per scan.

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