If you just want the bottom line: UndetectedGPT had the highest bypass rate (96%) and best readability (9.2/10) in our head-to-head testing against five major AI detectors. Undetectable AI came second with an 88% bypass rate and strong multilingual support. StealthGPT placed third at 82% with a handy Chrome extension.

But "best" depends on what you need. If multilingual humanization is your priority, Undetectable AI currently supports 30,000+ words across multiple languages for $19/month. If you want a browser extension for in-app humanization, StealthGPT has one. If you're on a tight budget, Humbot starts at $12/month and BypassGPT at $12/month.

For most people (students needing to pass Turnitin, writers avoiding AI detection flags, content creators publishing at scale), bypass rate and readability are what matter most. That's where UndetectedGPT wins. Keep reading for the full numbers, or skip to the comparison table.

Let's get the obvious thing out of the way: we built UndetectedGPT. Of course we think it's the best AI humanizer out there. If we didn't, we'd have serious problems. So yes, this comparison comes with a bias. We're not going to pretend otherwise.

But here's the thing: we're also the people who've spent thousands of hours studying how AI detectors work, testing every competing tool, and obsessing over bypass rates. That gives us a perspective most "neutral" review sites don't have. So instead of hiding behind fake objectivity, we're going to show you real numbers from real tests and let you draw your own conclusions. We'll even tell you where competitors beat us. Because if you can't trust a company to be honest about its weaknesses, you definitely can't trust it about its strengths.

We kept things simple and reproducible. We generated a single 1,000-word academic essay using ChatGPT (GPT-5), then ran it through every humanizer tool in this comparison. Each humanized output was tested against 5 major AI detectors: Turnitin, GPTZero, Originality.ai, Copyleaks, and ZeroGPT. The original essay scored 97-99% AI across all five.

Every tool was tested on its default settings with a standard academic mode (where available). We scored bypass rate as the percentage of detectors that returned a "human" or sub-20% AI verdict. Readability was scored by three independent reviewers on a 1-10 scale, averaging their assessments. Speed was measured from click to output. You could replicate this entire test yourself in an afternoon, and we'd encourage you to. Nothing we're sharing here requires you to take our word for it.

One important note: these results reflect a single test under controlled conditions. Your results may vary depending on the input text, the topic, the length, and the specific detector versions at the time of testing. That's why we emphasize testing for yourself before buying anything.

The numbers tell a pretty clear story, but let's dig into what actually matters.

Bypass rate is the headline stat, and there's a meaningful gap between the top and bottom of this list. UndetectedGPT at 96% means it passed nearly every detector, nearly every time. Undetectable AI at 88% is genuinely good: it'll work most of the time. But that 8-point difference matters when the one failure happens to be your Turnitin submission.

Readability is where a lot of tools quietly fall apart. A tool can technically "bypass" a detector by scrambling your text into something so weird it doesn't pattern-match as AI anymore. (This is the core difference between a paraphraser and a humanizer.) But if your professor reads it and thinks "this doesn't sound like a human either," you haven't solved anything. We tested readability separately from bypass rate for exactly this reason. UndetectedGPT scored highest at 9.2/10 because we optimize for both: text that passes detectors AND reads naturally.

On pricing, the range is wider than it used to be. Undetectable AI starts at $19/month for 10,000 words. StealthGPT starts at $32/month. WriteHuman starts at $18/month and Humbot at $12/month. GPTinf is $9.99/month for their Lite plan (20,000 words). The real differentiator is what you get per dollar. A tool with a 65% bypass rate at $19/month sounds comparable until you factor in the times it fails. UndetectedGPT's 96% bypass rate means you're almost never retesting or rewriting.

New additions since last year: BypassGPT ($12/month, 50+ languages) and HIX Bypass ($11.99/month, 50+ languages, built-in AI detector) have entered the market as budget options. Both support significantly more languages than most competitors, making them worth considering for non-English content. Their bypass rates lag behind the top performers, but if multilingual support at a low price point is your priority, they're worth testing.

We said we'd be honest, so here it is.

Undetectable AI supports more languages than we do. Their plan ($19/month, 10,000 words) covers multiple languages, and they offer a free tier of 1,500 words per month. If you need to humanize text in Spanish, French, German, or Mandarin, they're currently the better choice. We're working on multilingual support, but it's not live yet, and we're not going to pretend otherwise.

StealthGPT has a Chrome extension that lets you humanize text right inside Google Docs and other web apps. That's a genuinely useful feature we don't offer yet. They also have a unique "staircase" pricing model that gets cheaper the longer you stay subscribed, rewarding loyalty.

GPTinf is faster than us. About 4 seconds versus our 5. For most people that one-second difference doesn't matter, but if you're processing large volumes, it adds up. Their Pro plan ($24.99/month for 50,000 words) offers unlimited features.

BypassGPT and HIX Bypass support 50+ languages each. If you need to humanize content in Japanese, Arabic, Korean, or dozens of other languages, these tools currently serve markets we don't. Both also include built-in AI detectors so you can check your results without switching tools.

We're noting these because they're real advantages. If multilingual support, a browser extension, or rock-bottom pricing is your top priority, one of these tools might genuinely be the better fit for you right now.

Now for the part where we get to brag a little, backed by the numbers above.

The 96% bypass rate isn't just the highest in this comparison. It's the highest we've seen from any humanizer tool, period. We tested against the same 5 detectors that every student, content creator, and professional worries about: Turnitin, GPTZero, Originality.ai, Copyleaks, and ZeroGPT. And we passed nearly every time. That includes Turnitin's August 2025 bypasser detection update, which specifically targets humanized text. (For a full walkthrough on Turnitin, see our Turnitin AI detection guide.)

But here's where it gets interesting: high bypass rates usually come at a cost. Most tools that aggressively rewrite text to dodge detectors end up producing output that sounds off. Robotic in a different way. We managed a 9.2/10 readability score while maintaining that bypass rate, which means the text actually sounds like a human wrote it. That combination is rare because it requires optimizing for two things simultaneously: statistical pattern restructuring (to beat detectors) and semantic preservation (to keep it readable).

The value per dollar is another area where we're confident. The highest bypass rate (96%) paired with the best readability (9.2/10) means you're not retesting, rewriting, or second-guessing the output. One pass, done. And our free tier of 500 words per day is the most generous daily allowance available, enough to actually test the tool properly before committing to a subscription. You can prove to yourself that it works before spending anything.

Different situations call for different tools. Here's our honest recommendation based on specific use cases.

You're a student submitting to Turnitin: UndetectedGPT. Bypass rate is everything here, and the 96% rate against Turnitin specifically (including their 2025 bypasser detection update) is the highest available. A failed Turnitin check isn't a "try again" situation; it's a misconduct allegation. (Learn more about what's at stake in can universities detect ChatGPT?.) Don't gamble with cheaper tools when the stakes are your academic record.

You need multilingual humanization: Undetectable AI for major European and Asian languages with the best combination of quality and language coverage. BypassGPT or HIX Bypass if you need 50+ languages at a lower price point and can accept a lower bypass rate.

You're a content creator publishing in English at scale: UndetectedGPT for highest quality, or Undetectable AI's Standard plan ($24/month for 75,000 words) if you need high volume at a lower per-word cost. At scale, the time saved from not retesting failed outputs pays for the price difference.

You're on a tight budget: Humbot ($12/month) or BypassGPT ($12/month) are the cheapest options with passable performance. But remember: a tool with a 72% bypass rate that costs $12/month isn't actually cheaper than a tool with 96% bypass rate at $19.99/month if you have to rewrite the 28% that fails.

You want to humanize inside your browser: StealthGPT is the only option with a Chrome extension for in-app humanization. Useful if your workflow lives in Google Docs or web-based editors.

You just want to check before you buy: Use the free tiers. UndetectedGPT offers 500 words/day (the most generous daily allowance). Undetectable AI offers 1,500 words/month. Paste the same text into both, run both outputs through GPTZero or Originality.ai, and compare. Your own testing is what should actually convince you.

If what you care about most is bypass rate and readability (and honestly, those should be your top two criteria), UndetectedGPT is the clear winner in this comparison. The highest bypass rate (96%) paired with the highest readability score (9.2/10) means you're getting text that both fools detectors and actually sounds like you wrote it. There's a free tier so you can see the results before paying anything.

Undetectable AI is a strong second choice, especially if you need multilingual support. StealthGPT earns its spot for anyone who needs a browser extension. And the budget options (BypassGPT, Humbot) are fine for low-stakes use where occasional failures aren't catastrophic.

But we genuinely mean it when we say: test for yourself. We have the most generous daily free tier in this comparison specifically because we want you to compare us against whatever else you're considering. Paste the same text into UndetectedGPT and any competitor. Run both outputs through GPTZero or Originality.ai. Read them side by side. The numbers in this article are a starting point, not the final word. Your own testing is what should actually convince you.