GPTInf Review: Does It Really Work?

🧠 Introduction

GPTInf claims to be the #1 ChatGPT humanizer — offering a suite of tools including an AI humanizer, AI detector, keyword freezing, and unlimited re-paraphrasing on higher-tier plans.

But does it actually bypass AI detectors like GPTZero, ZeroGPT, and Turnitin?

We put it to the test — and compared it with TwainGPT, the leading AI humanizer in 2025.

🚀 What Is GPTInf?

GPTInf is an AI rewriting and detection tool that claims to:

• Humanize AI-generated content
• Detect AI vs human writing
• Offer “freeze keywords” for control
• Re-paraphrase content on demand

It’s accessible via their website and is also widely used as a plugin in the ChatGPT GPT Store, where it has over 9 million conversations. This plugin traffic seems to make up the bulk of its user base.

💸 Pricing Breakdown

GPTInf offers three paid plans and a limited free tier:

✅ Yearly plans save 50%, which is a generous discount.

🚫 Free tier:

• 120 words without signing up
• Another 120 words after account creation
• But no free retries, unlike TwainGPT

🔍 AI Detector Performance

GPTInf’s AI detector performed well in our tests:

• It correctly flagged human-written content as human
• It also accurately detected GPT-5 content as AI

However, there’s a serious trust issue between GPTInf’s own humanizer and its own detector — which we’ll explain below.

🧪 Humanizer Test Results

We tested GPTInf’s AI humanizer with a 100% GPT-5-generated text using default settings.

Detection Results After Humanizing:

While the GPTZero score slightly dropped, the humanizer still failed to bypass every major detector.

And worse — the rewrite quality degraded noticeably:

• 🟥 Sentence structure became clunky
• 🟥 Phrasing was awkward
• 🟥 Original meaning was lost

The “humanized” version looked more suspicious than the original.

🔁 Contradiction in Detection

Here’s where things get seriously shady:

• GPTInf’s humanizer claimed the rewritten text was 1% AI and labeled it “human-written.”
• But when we pasted that same result into GPTInf’s own AI detector, it came back as 99% AI.

🚨 That’s a major red flag.

If GPTInf’s humanizer can’t bypass its own detector, it certainly won’t bypass Turnitin or GPTZero in any academic or real-world use.

🧊 “Freeze Keywords” Feature

GPTInf includes an option called Freeze Keywords that lets users protect specific words from being changed during rewriting.

👍 Pros:

• Useful for preserving names, citations, and key terms.
• Offers more control over the rewrite.

⚠️ Cons:

• GPTInf clearly warns this will lower the bypass success rate.

Note: We did not use this feature in our tests — all results were generated using default settings

🆚 TwainGPT Comparison

We ran the exact same GPT-5 text through TwainGPT.

TwainGPT Detection Results:

TwainGPT clearly outperforms GPTInf.

✅ Final Verdict

GPTInf has a solid AI detector and a decent UI, especially within the ChatGPT plugin ecosystem.

But the core product — the AI humanizer — simply doesn’t deliver:

• ❌ Failed to bypass GPTZero, ZeroGPT, and Turnitin
• ❌ Ruined the text quality with awkward phrasing
• ❌ Couldn’t even bypass its own AI detector

If you're trying to bypass AI detectors, GPTInf isn't the answer.

✅ Use TwainGPT instead — the best AI humanizer in 2025.

📌 FAQ

Is GPTInf free?

You can humanize up to 240 words for free.

Can GPTInf bypass GPTZero or Turnitin?

No. In our tests, GPTInf failed to bypass all major detectors.

Is GPTInf’s AI detector accurate?

Yes, it even flagged its own humanizer output as AI.

What’s better than GPTInf?

The best alternative to GPTInf is TwainGPT.