Is Undetectable AI free?

Partly. Its humanizer page offers a free basic model with no signup, which its own FAQ says may be flagged by detectors. The free trial of its main model is limited to 250 words, according to its pricing page .

How much does Undetectable AI cost?

Its pricing page lists 10,000 words a month at $5.00 a month billed annually ($60), with a $9.99 figure also shown, and 20,000 words a month at $9.50 a month billed annually ($114). Prices appear without a currency code.

What is a good Undetectable AI alternative for ChatGPT drafts?

If you want a free editing pass with no detector pitch, our box takes 20 to 1,000 words per run in Casual, Professional or Academic tone with no account. Grammarly's AI Humanizer is another writing-first option.

Does Undetectable AI really refund you if text is flagged?

The vendor says so: its pricing page says it will refund the cost of humanization if output is flagged as not human. Read the terms on its help page before relying on it.

Undetectable AI Alternative for ChatGPT Text

Updated November 8, 2026. Features and prices were read on each vendor's own page on November 8, 2026.

Undetectable AI vs ChatGPT Humanizer: the published facts

Same fields as our best ChatGPT humanizer comparison, read on November 8, 2026. Undetectable AI shows prices with a dollar sign and no currency code.

Field	ChatGPT Humanizer (this site)	Undetectable AI
Free use	Yes	Yes, basic model; free trial of the main model capped at 250 words
Signup for free use	No	No for the basic model
Words per run	20 to 1,000	Up to 10,000 characters
Tones or modes	Casual, Professional, Academic	Basic and Stealth; 5 purposes; reading levels
Languages	Not specified	50+, English as main focus
Lowest paid price listed	No paid plan listed	$5.00 a month billed annually ($60) for 10,000 words a month; $9.99 also shown
Vendor's detector claim	None; says it cannot promise detector scores	Says output scores as human; offers a refund if flagged
Source	Our box	AI Humanizer page, pricing page

Free, trial and paid: three tiers that are easy to mix up

Undetectable AI publishes three different levels of access, and the words "free" and "trial" mean different things on its pages.

The free basic model. The Undetectable AI humanizer page is titled "Free AI Humanizer (Unlimited, No Signup)". Its FAQ says the free version uses a basic model and "may be flagged by detectors".
The free trial. The same FAQ points users to a free trial for the main model, and the Undetectable AI pricing page says the free trial is limited to 250 words.
Paid plans. The pricing page lists 10,000 words a month at $5.00 a month billed annually ($60), 20,000 words at $9.50 a month billed annually ($114), and larger plans above that. It also shows a $9.99 figure beside the first plan.

So the large free run belongs to the basic model, and the model the vendor recommends is a 250 word trial before you pay. Keep that in mind when you compare free tiers.

Characters versus words

Undetectable AI states its run size in characters: up to 10,000 in one go, on its humanizer page. Most tools, including ours, count words. English prose averages several characters per word once spaces are included, so 10,000 characters is longer than our 1,000 word cap. You can paste more into one free Undetectable AI run than into ours. That's a genuine advantage for long drafts on the free basic model.

How the two tools are framed

This is the biggest difference, and it's about the pitch rather than the output.

Undetectable AI's humanizer page leads with detector scores: its headline promises to "score as human in detectors", it shows sample detector percentages before and after, and it offers a refund if humanized text is flagged. Those are the vendor's claims, and we don't rank tools on detector claims.

Our box makes no promise about detectors. No rewrite tool can honestly tell you how a detector will score your text, because detectors differ and change. We frame the box as an editing aid: it changes rhythm, stock phrases and hedging, and you make the last pass.

If you're a student, that framing matters. A tool sold on avoiding detection doesn't change your course rules on AI use. Check them, and disclose when asked.

Where Undetectable AI is ahead

On published features:

Bigger free runs on the basic model (10,000 characters, per its humanizer page).
More settings. Purpose (General Writing, Essay, Article, Marketing Material, Story) and readability levels, plus Basic and Stealth modes.
More languages. More than 50 listed on its humanizer page, with English as the main focus.
More tools. An AI detector, paraphraser, essay writer, browser extension and API on the same account.

Where our box is the simpler choice

One free tier, one model. What you run free is the only thing we offer. There is no better model behind a trial.
No account and no email for any tone.
Writing first. Three tones aimed at how the draft reads, with guides on the specific habits of ChatGPT drafts.
Clear caps. 20 to 1,000 words per run, 5 runs a minute and 20 a day per connection.

The fairest test is your own draft. Paste a ChatGPT paragraph into our rewrite box and the same paragraph into Undetectable AI's free tier, then read both out loud.

Who should stay with Undetectable AI?

Stay with Undetectable AI if:

You need settings for purpose and reading level, for example a story versus a marketing page.
You write in one of the 50+ languages its humanizer page lists.
You want an API or a browser extension.
You value its refund offer and are comfortable with its terms; read them on its own help page first.
You routinely paste drafts longer than 1,000 words and want the free basic model's larger run.

Switching from Undetectable AI: what to know

There's nothing to export. Copy any humanized text you want to keep out of your Undetectable AI account first, since our box stores no history.

If you have a paid plan, read the billing terms on the Undetectable AI pricing page before you cancel, and note whether your plan bills monthly or annually. And if you relied on its purpose and reading level settings, you'll need to do that part by hand with us: pick the closest tone (Academic for an essay, Professional for an article, Casual for a story) and adjust the vocabulary yourself.

How we compared the two

We filled the same fields as every comparison on this site, from each vendor's own pages, on November 8, 2026. We confirmed undetectable.ai as the official domain before citing it. The full method is on how we test humanizers: three sample drafts (a short essay paragraph, a work email and a product description), checked for meaning kept and readability.

This page weighs published features and limits only.

Comparing more detector-focused tools? Our BypassGPT alternative page covers a tool with an 80 word free input, and the StealthGPT alternative page covers a paid workspace with three rewrite models. For a smaller tool with its own word-based plans, see the Humbot alternative page.