Undetectable AI is a humanizer: you paste in text another AI wrote, and it rewrites it so AI detectors read it as human. The main alternatives do one of two things. Most are other humanizers: WriteHuman, StealthGPT, HIX Bypass, Humbot, BypassGPT and QuillBot's AI Humanizer. The other kind is a model that writes like a person in the first place, so there is nothing to humanize afterwards. That is Hemmingway-1.5, which we make: in our own published test, 90% of its writing passed GPTZero and four other top AI detectors on the first try.
We have tested Hemmingway-1.5 and nothing else on this page. Every other tool is described from its own site, as it read on 27 October 2026.
What Undetectable AI is
By its own site, Undetectable AI has three main tools: an AI detector, a humanizer that makes stiff or robotic text read naturally, and an AI image detector. Its menus also list a paraphraser, an essay writer and a plagiarism checker. Its home page says the humanizer's output scores as human on every major detector, without naming which. Its plans are sold by words a month, from $9.99 a month for 10,000 words, or $5 a month billed yearly, and its free trial is limited to 250 words.
The alternatives, by what you want instead
- To skip the second step: Hemmingway-1.5. Ask for the text and it writes it, or paste AI text in and it rewrites it. See undetectable AI for the test.
- A sentence-by-sentence check: WriteHuman. Its built-in detector marks how likely each sentence is to be AI.
- A quick free rewrite of something short: QuillBot's AI Humanizer, which sits next to its paraphraser.
- A study bundle: Humbot, with a humanizer beside a homework helper, flashcards and a citation tool.
- A humanizer plus a writer: StealthGPT, which also drafts essays with citations.
- Other humanizers sold on bypassing detectors: HIX Bypass and BypassGPT.
Side by side
| Tool | Kind | Tested by us | Free use, by its own page |
|---|---|---|---|
| Undetectable AI | Humanizer, detector, writing tools | No | Free trial up to 250 words |
| Hemmingway-1.5 | A writing model and app | Yes: 90% passed GPTZero and four other detectors | Free to try, no card |
| WriteHuman | Humanizer with a detector | No | A free trial |
| QuillBot AI Humanizer | Humanizer next to a paraphraser | No | Short texts, with limits |
| Humbot | Study tools with a humanizer | No | A free trial for new users |
| StealthGPT | Humanizer and a writer | No | A small free tier |
| HIX Bypass | Humanizer | No | A free trial |
| BypassGPT | Humanizer | No | Free to try |
Hemmingway-1.5
Hemmingway-1.5 is our writing model, 27B, with open weights. It is the default model in the Hemmingway app on Mac, Windows, Android and the web. We had it write 1,848 texts in 13 kinds of writing and ran each once through GPTZero, Fakespot, Vanguard, WasItAIGenerated and MELD: 90% passed. Real human writing passed the same detectors 86% of the time. When it rewrites AI text instead, 89% of its rewrites passed, by its Hugging Face card. It is free to try, and plans are on pricing. Our AI detector test has the method and every number.
Where it is weaker: it is English-first, and it is better at short writing than long.
WriteHuman
WriteHuman rewrites text from ChatGPT, Claude, Gemini and others, changing sentence length, word choice and cadence. Its own detector scores each sentence, and its site prints its own scores for eight detectors. Plans were listed at $12, $19 and $39 a month.
QuillBot's AI Humanizer
QuillBot's humanizer rewrites AI drafts for tone, clarity and flow, in several languages, next to QuillBot's paraphraser and grammar checker. Its own page says it is not a tool for evading AI detection. The free version handles short texts.
Humbot
Humbot is a set of study and writing tools with a humanizer among them. It says its output gets past Turnitin, GPTZero and other detectors, and shows no test results for that on its home page.
StealthGPT
StealthGPT has a humanizer, a writer that drafts essays with citations, and a browser extension. It names twelve detectors it says it beats and prints its own scores. It markets the extension for quiz, test and homework answers.
HIX Bypass and BypassGPT
Both are humanizers sold on getting AI text past detectors. HIX Bypass lists GPTZero, Originality.ai, Copyleaks and others, and pitches drafts for essays and assignments. BypassGPT names ZeroGPT, GPTZero and Originality.ai, and says it is free to try.
How to choose
- Do you already have the text? If it is written and you only want it to read better, a humanizer or Hemmingway's rewrite will do. If you have only the facts, use a writer and skip a step.
- Do you need to see the check? WriteHuman and Undetectable AI put a detector beside the rewrite. Treat any score as a guess: in our test, detectors flagged 14% of writing by real people.
- Try before you pay. Every tool here has a free trial or a free tier of some kind.
Try HemmingwayDownload the app
Common questions
What is the best alternative to Undetectable AI?
It depends on what you want. If you want to skip the humanizing step, Hemmingway-1.5 writes text that passed GPTZero and four other detectors 90% of the time in our test. If you want another humanizer with a sentence-by-sentence detector, WriteHuman offers that. We have not tested the humanizers, so we do not rank them.
Is there a free alternative to Undetectable AI?
Hemmingway is free to try with no card. QuillBot's humanizer handles short texts for free, and WriteHuman, Humbot, HIX Bypass, BypassGPT and StealthGPT each list a free trial or a small free tier on their sites.
Is Hemmingway a humanizer?
It is a writing model first: it writes the text from your request. It also rewrites AI text you paste in, and its AI humanizer opens the app with your text filled in.