AI text humanisers compared

QuillBot AI Humanizer

Part of a suite of writing tools with a paraphraser, a plagiarism checker and a citation generator. According to the vendor, it rewrites text so that it sounds natural and keeps its meaning. It does not promise to get past detectors.

Strength:a widely used tool that says openly it does not guarantee the result with a detector; it handles German too.

Limit:Czech and Slovak are not among the languages the vendor lists, and the free version only rewrites a short passage at a time.

Grammarly AI Humanizer

A free humaniser from Grammarly with four preset styles and a custom style based on a sample of your writing that you paste in. The vendor states explicitly that the tool is not meant for getting around AI detectors.

Strength:it is free, can adapt to your style and takes a clear stance on getting around detectors; it handles German too.

Limit:Czech and Slovak are not among the supported languages, and on individual accounts texts are used for training by default until you switch it off.

Undetectable AI

A humaniser built on the promise that the text will pass AI detectors. It offers rewrite modes, a choice of level and purpose for the text, its own detector and a browser extension. The vendor promises a refund if a detector flags the rewritten text.

Strength:fine-grained rewrite settings and explicitly listed support for Czech, Slovak and German.

Limit:the vendor itself describes languages other than English as secondary, and the privacy policy says nothing about the texts you paste in.

StealthGPT

The humaniser that promises most emphatically to get past detectors: according to the vendor, the text will pass all the major detectors, including GPTZero and Turnitin. On the same page it also states that no tool can guarantee getting past them one hundred per cent of the time, because detectors change.

Strength:the widest range of connections to other tools — an API, a browser extension, WordPress and Zapier.

Limit:the figures for the number of languages contradict each other across the site, Czech is not listed explicitly, and the privacy policy says nothing about the texts you paste in.

HIX Bypass

A humaniser with several rewrite modes and a built-in detector. The vendor promises that the text will pass detectors such as GPTZero or Originality.ai “Without Fail”.

Strength:Czech, Slovak and German are explicitly among the supported languages, and you can check the result straight away.

Limit:nobody has independently verified the promise of getting past detectors, and the privacy policy does not say what happens to the text you paste in.

Humbot

A suite of tools for studying and writing: a humaniser, an AI detector, a plagiarism checker and a translator. According to the vendor, it helps text pass even strict detectors, and it promises a “100% Human Score”.

Strength:its home page explicitly promises that it does not store or share documents or train on them.

Limit:language support is described inconsistently across the site, Czech is not listed explicitly, and the free limits are not stated.

Measured before and after the rewrite

We measure the text before and after the rewrite — sentence rhythm, phrases typical of AI and repetition. The analysis shows the original and the humanised text side by side, what we removed and which checks passed.

We watch the content and the length

The rewrite is meant to keep the facts, numbers, names and quotations, and afterwards we check the length: if the word count changes by more than a quarter, the text is repaired. We do not verify the facts automatically, though, so always read the result.

Czech, Slovak and German are not afterthoughts

For each of the four languages, English included, we keep our own list of phrases typical of AI and our own rewrite rules for each document type, from an essay to a cover letter.

A rewrite in your style

From your sample texts we calculate sentence length, punctuation and your most frequent linking words, and the rewrite adapts to them. Every finished humanisation that passes the checks becomes a sample too.

Detection in the same place

After the rewrite you can run the text through detection and see what seven detectors say about it side by side, including two separate models, OpenAI and ZeroGPT.

Your texts stay yours

Without signing in we do not store the text at all — it is rewritten and discarded. With an account it is kept only in your history and used only to sharpen your own detection and humanisation. We do not train any shared model on it, do not use it for our own purposes, do not sell it, and one button deletes your whole history.

Free, with a paid plan on top

Without signing in you get two rewrites per 30 days; a free account gives five, longer texts and the deep rewrite. The Pro plan mainly adds volume — 200 humanisations a day — and uploading your own sample texts.

What you will not find here

No promise that the text will pass a detector, no refund for flagged text, no choice of tone and no browser extension. Humanisation changes the form of a text, not who wrote it.

Does it keep the facts and numbers?

Paste a text with names, years and numbers, and compare them after the rewrite. A humaniser that changes a fact does more harm than a machine-like style.

Does it handle your language?

Test it on a text in the language you actually write in. A tool built for English often returns sentences in other languages that are grammatically fine but do not sound natural.

Does it show what it changed?

If all you get is the finished text, you have to read the whole thing again. An overview of the changes and a measurement before and after the rewrite save you time and uncertainty.

What does it promise?

Nobody has independently verified the promise that a text will pass every detector, and detectors keep changing. A tool that mainly sells this promise is selling something it cannot guarantee.

What does it do with your text?

Check whether the text you paste in is stored and whether it is used for training. For some tools the privacy policy does not address this at all.

Is there a humaniser that reliably gets past detectors?

No. Independent studies reach different results depending on which tool and which detector are tested, and the detectors change in the meantime. Even vendors who promise to get past detectors admit on their own websites that it cannot be guaranteed one hundred per cent.

Is using a humaniser cheating?

It depends on what you use it for and what the rules allow. Editing your own text is ordinary editorial work. Using a humaniser to hide undisclosed use of AI in submitted work is another matter — Charles University in Prague, in its guidance on theses, states that undisclosed use of AI can lead to a negative assessment of the defence or to disciplinary proceedings.

Why do humanisers promise undetectability when nobody can guarantee it?

Because it is the main reason people look for them. A 2026 study of how humanisers are marketed describes how their websites usually do not mention academic ethics and present getting around detectors as a reasonable response to detectors being unreliable.

Which humaniser is best for languages other than English?

It cannot be settled from the outside. Most of these tools are built for English and either do not support languages such as Czech or explicitly class them as secondary. The best test is your own text: put the same paragraph into two or three tools and compare which one kept the content and sounds natural in your language.