Undetectable AI is a paid AI humanizer that rewrites AI-generated text to look human to detectors. It starts at $9.99 a month for 10,000 words, or $5 a month billed yearly. It does make text read more naturally. But independent tests by GPTZero and Originality.ai found their detectors still flagged its output as AI, so don’t treat the name as a promise.
We ran our own sample through its free, no-signup mode on November 1, 2026, checked the official pricing page, and read the two most detailed detector tests published so far. Here’s what we found.
Undetectable AI pricing
| Words per month | Monthly billing | Yearly billing |
|---|---|---|
| 10,000 | $9.99/mo | $5.00/mo ($60 a year) |
| 20,000 | $19.00/mo | $9.50/mo ($114 a year) |
| 35,000 | $31.00/mo | $15.75/mo ($189 a year) |
| 50,000 | $42.50/mo | $21.25/mo |
Source: Undetectable AI pricing page, checked November 1, 2026. Larger plans go up to 380,000 words a month, and business plans with non-expiring credits are priced on request.
The free trial is limited to 250 words. Without an account, you can still run text through a “Basic” public model. The stronger “Stealth” and “Undetectable” modes need a free sign-up.
Our test: what the free mode does to a paragraph
We used the same 124-word AI-written paragraph from our free AI humanizer test, pasted it into the homepage humanizer without an account, and kept the default settings (University readability, General Writing, Balanced).
| Original | Undetectable AI (Basic, free) | |
|---|---|---|
| Length | 124 words | 102 words |
| Opening | “Artificial intelligence is transforming the way businesses approach content creation.” | “Artificial intelligence is changing how companies create content.” |
| Style changes | Long sentences, “However”, “As a result”, “Ultimately” | Shorter sentences, “But there’s a catch.”, “So,” and plainer wording |
| Meaning | Kept, with small losses (“genuinely valuable” became “really valuable”) |
The rewrite reads better than most free humanizers we’ve tried. It cut the stock transitions that make AI text easy to spot, and it didn’t introduce grammar mistakes. It also dropped about 18% of the words, so check that nothing important went missing.
We couldn’t run the result through GPTZero because we’d used up its free guest scans in our earlier test. The tool itself showed a warning that “AI detectors might still flag your text with the Basic Public Model”. In other words, Undetectable AI doesn’t claim the free mode passes detectors.
What independent tests found
| Tester | What they ran | Result after humanizing |
|---|---|---|
| Originality.ai (August 2026) | One ChatGPT article on brand marketing | Originality.ai: 100% AI. GPTZero: 91% AI. Writer.com: 3% AI |
| GPTZero (updated January 2026) | Two paragraphs of a ChatGPT essay, University setting | Still flagged as “likely AI” |
Both testers sell AI detectors, so they have a reason to publish results like these. Still, the pattern matches what we’ve seen across humanizers: weaker detectors like Writer.com are easy to get past, while GPTZero and Originality.ai usually aren’t. We explain why in do AI humanizers actually work.
Other features
- AI detector with unlimited checks on paid plans. Use an independent detector too, since a humanizer’s own detector has an obvious bias.
- Paraphraser, essay writer and SEO writer tools on the same account.
- Chrome extension for Google Docs, Gmail and web pages.
- “Human Auto Typer”, which types text into a document as if a person were writing it. Its obvious use is faking a document’s typing history, which many schools check. We’d steer clear: if a school is checking typing history, using this is the kind of thing that turns an AI question into a cheating case.
- Money-back guarantee “if output flagged is not human”, according to the pricing page. Read the terms for which detectors and conditions count before relying on it.
Who it’s for, and who should skip it
Reasonable fit: marketers and bloggers who want AI drafts to read less stiffly, and who’ll edit the result anyway. The free Basic mode is enough to see whether you like its style.
Poor fit: students trying to get AI-written work past school checks. Strong detectors still catch it in published tests, and using AI where it’s banned is a policy problem no matter what a detector says.
Undetectable AI vs alternatives
| Tool | Entry price | Notes |
|---|---|---|
| Undetectable AI | $9.99/mo (10K words) | Better-than-average rewrite quality; free Basic mode without sign-up |
| Grubby AI | $14.99 per 4 weeks | Failed GPTZero and Originality.ai in published tests |
| Clever AI Humanizer | Free | Lowered GPTZero from 100% to 29% AI in our October test, but the writing got clumsier |
FAQs
Is Undetectable AI free?
Partly. You can use the Basic model without an account, and the free trial covers 250 words. Paid plans start at $9.99 a month, or $5 a month billed yearly.
Does Undetectable AI really work?
It makes text read more naturally, but GPTZero and Originality.ai both still flagged its output as AI in their published tests. It does better against weaker detectors.
Can Turnitin detect Undetectable AI?
No independent Turnitin test has been published, because Turnitin is only available to institutions. Humanized text is still AI-written, so it’s still against the rules wherever AI isn’t allowed.
Is Undetectable AI safe to use?
It’s an established paid service. As with any online rewriter, don’t paste confidential work or personal information, and check its privacy policy before uploading files.
