Free tool, no sign-up
Humanize AI Text: Free Tool With Word-Level Diff
Paste a draft. Every paragraph is rewritten separately, and you see exactly which words changed against the original before you use any of it.
Uniform sentence lengths are the clearest machine tell.
Stops every point being built to the same template.
"It is worth noting", "delve", "leverage", restating closers.
Replaces them with a colon, comma or new sentence.
What this does, in 30 seconds
Humanize AI Text is a free, no sign-up tool from StartupHub.ai that rewrites AI drafts paragraph by paragraph. You choose how much to rewrite (Light, Balanced or Thorough) and which tells to target: uniform sentence rhythm, repeated structure, filler phrases and em-dashes. It returns a word-level diff showing added words highlighted and removed words struck through, plus the share of your original wording that survived, so you can check the result rather than trust it. Rewriting also breaks statistical SynthID and AI watermark patterns as a side effect, because a new model picks a fresh set of words. It makes no claim about defeating AI detectors, because detectors guess and are unreliable in both directions.
The actual tells
Why AI drafts still sound like AI
Not vocabulary. The giveaways are structural, which is why swapping synonyms never fixes a draft and why each of these has its own switch.
Every sentence is the same length
Human writing lurches. A long clause, then four words. Models produce a metronome, and the regularity is what your ear picks up before you can name it.
Three consecutive sentences of 18, 19 and 18 words.
The same shape under every point
A claim, an explanation, an example, in that order, under all six headings. One paragraph built that way reads fine. Six in a row reads generated.
Every section opening "X is important because..." and closing "...which is why it matters."
Filler that survives deletion
Phrases that can be cut without losing a single fact. They pad rhythm and signal nothing.
"It is worth noting that", "delve into", "leverage", "in today’s rapidly evolving landscape".
Em-dashes everywhere
The single most recognisable punctuation habit in machine writing, and the one readers name most often. A colon, a comma or a full stop nearly always reads better.
Two or more em-dashes in a paragraph that has no other punctuation variety.
Measured, not illustrated
Before and after, same paragraph
Real output from this tool with all four switches on. Paste the same paragraph and you should get something comparable. Light barely moving is the real result, shown as measured.
Original
It is worth noting that leveraging AI-powered solutions can significantly enhance operational efficiency. Moreover, organizations that embrace these transformative technologies are well-positioned to unlock unprecedented value in today’s rapidly evolving landscape.
Light
94% of the original words survivedIt is worth noting that leveraging AI-powered solutions can significantly enhance operational efficiency. Moreover, organizations that embrace these transformative technologies are well-positioned to unlock unprecedented value in today’s rapidly evolving landscape.
Left the filler in place. On a paragraph this generic, Light is too conservative to help.
Balanced
38% of the original words survivedAI-powered tools can meaningfully boost operational efficiency. What’s more, organizations that adopt these technologies stand to create real value in today’s fast-changing environment.
Cut "It is worth noting that" and "leveraging", and traded "Moreover" for something people say.
Thorough
26% of the original words survivedAI-driven tools can dramatically boost how efficiently operations run. Companies that adopt these game-changing technologies also position themselves to capture value that was previously out of reach in today’s fast-changing market.
Rebuilt both sentences. The facts survive, almost none of the wording does.
How it works
Three steps, and you check the result
Paste your draft
One blank line between paragraphs. Each one is handled separately, which is why the progress bar counts real work instead of animating.
Pick how hard to rewrite
Light is a proofread. Thorough rebuilds every sentence from scratch, keeping only the facts. Four extra switches handle rhythm, structure, filler and em-dashes.
Read the diff before you use it
Added words highlighted, removed words struck through, and the share of your original wording that survived. Nothing is hidden behind "trust us".
What makes it different
Controls, not one magic button
You see every word that changed
Original and rewrite side by side, word-level. Most humanizers hand back a block of text and ask you to take it on faith. You should not have to, least of all with something you are about to publish under your own name.
Controls, not one magic button
Uniform sentence length and a template repeated under every point are what make a draft read as machine-assembled. Those are the switches, because those are the actual tells.
Paragraph by paragraph
A model holds its voice over a paragraph far better than over a whole essay, and one failed paragraph keeps its original text rather than costing you the document.
Comparison
How this differs from other AI humanizers
Everything in the right-hand column is what those tools advertise on their own pages. We have not run their output through anything, and we are not going to claim we did.
| This tool | Typical AI humanizer | |
|---|---|---|
| Shows what changed | Word-level diff, added and removed | Returns a block of text |
| Controls | Strength plus rhythm, structure, filler, em-dashes | One button |
| Claims about AI detectors | None. Detectors guess, in both directions | Usually advertises beating them |
| Price | Free, no sign-up | Free trial, then paid |
| API | POST /api/v1/rewrite | Paid tiers only |
Questions
Straight answers
Will this remove a watermark or SynthID from my text?
In practice, yes, and it is worth understanding why rather than taking it on faith. Text watermarking such as Google DeepMind's SynthID-Text or Anthropic's does not attach anything to your document. It nudges which words the model picks as it writes, leaving a statistical pattern across those choices. Rewriting the passage produces a new set of word choices, made by a different model that does not apply that scheme, so the original pattern does not carry over. Two honest caveats: this is a side effect of rewriting, not a guarantee, and lightly edited text keeps more of the original pattern than heavily rewritten text. Separately, AI detectors are not watermark readers. They guess from style, they are unreliable in both directions, and nothing here promises anything about them.
What is the difference between Light, Balanced and Thorough?
How much of your original wording survives. Light is a proofread: it fixes what reads as machine-written and leaves the rest alone. Balanced rewords where it helps. Thorough rebuilds every sentence from scratch, keeping only the facts. Measured on the sample paragraph shown above, on the same day, the three modes kept 94, 38 and 26 percent of the original words. Light doing almost nothing there is real: on a paragraph that is generic throughout, it is often too conservative to help, and Balanced is the better starting point.
Does it change what my text says?
It is instructed not to: no new facts, names, numbers or claims, and none removed. It is a line edit, not a rewrite of your argument. That said, these are language models, and the whole reason the diff is on the page is so you can check rather than assume. Read it before you publish.
What does the similarity number mean?
The share of your original words that survived. A light edit lands high, often above 80 percent. Turning on every option and choosing Thorough typically lands in the 20s or 30s, because cutting filler and restructuring sentences genuinely replaces most of the wording.
Is it free, and is there a limit?
Free, no sign-up. It runs on free-tier models, so expect a few seconds per paragraph, and occasionally a paragraph comes back unchanged or the request fails outright because every free model was rate limited at that moment. The page tells you when that happens instead of passing your input off as a rewrite.
Can I use it from my own code?
Yes. POST to /api/v1/rewrite with an API key and it returns the rewritten text plus the same per-paragraph diff statistics the page shows, so it drops into an Apify actor or a Fly worker without scraping this page.
Free tool
Every word that changed, in front of you.
No sign-up. If you want it in a pipeline instead, the same rewrite runs at /api/v1/rewrite.