Best ChatGPT AI Humanizer Tools in 2025 (Tested on GPT-4)
The best tools to humanize ChatGPT output specifically. We tested each humanizer on real GPT-4 content and ranked by bypass rate, quality, and price.
ChatGPT content has distinctive writing patterns — formal phrasing, predictable sentence structure, and overuse of transition words. Here are the best tools to humanize ChatGPT output.
Why ChatGPT Specifically Needs Humanizing
Common GPT-4 signatures include:
- Consistent sentence length (typically 15–25 words)
- Overuse of “Furthermore,” “Moreover,” “In conclusion,” “It is worth noting”
- Lists and headers at predictable intervals
- Passive voice overuse
The 5 Best ChatGPT Humanizer Tools
1. Undetectable AI (Best for GPT-4 Bypass) — 4.9/5
| Detector | Before | After Undetectable AI |
|---|---|---|
| GPTZero | 96% AI | 7% AI |
| Grammarly | 91% AI | 11% AI |
| Originality.ai | 98% AI | 9% AI |
| Turnitin | 94% AI | 14% AI |
Price: $9.99/month
2. QuillBot Fluency Mode (Best Free ChatGPT Humanizer) — 4.6/5
| Detector | Before | After QuillBot Fluency |
|---|---|---|
| GPTZero | 96% AI | 29% AI |
| Grammarly | 91% AI | 27% AI |
| Originality.ai | 98% AI | 43% AI |
Free tier: 125 words per paraphrase
3. ChimpWrite Free AI Humanizer (Best Free for Longer Content) — 4.0/5
Our free AI humanizer handles 500 words per request with no signup.
| Detector | Before | After ChimpWrite |
|---|---|---|
| GPTZero | 96% AI | 34% AI |
| Grammarly | 91% AI | 31% AI |
4. WriteSonic Humanizer (Best for Marketing Copy) — 4.1/5
Performs particularly well on ChatGPT-generated marketing content.
5. Humanize.pro (Best for Daily ChatGPT Content) — 4.2/5
~300 words/day free. Good for daily AI-assisted article workflows.
Tips for Humanizing ChatGPT Content
- Remove GPT filler phrases before humanizing (“Furthermore,” “In conclusion,” “It is worth noting”)
- Break long content into 300–500 word chunks for better results
- Choose medium intensity — high intensity can degrade quality
- Always verify with GPTZero after humanizing
ChatGPT Humanizer Comparison Table
| Tool | GPT-4 Bypass (GPTZero) | Turnitin Bypass | Free Tier | Price |
|---|---|---|---|---|
| Undetectable AI | Excellent (7% AI) | Excellent | Trial | $9.99/mo |
| QuillBot Fluency | Good (29% AI) | Moderate | 125 words | $9.95/mo |
| ChimpWrite | Good (34% AI) | Weak | 500 words | Free |
| WriteSonic | Good (27% AI) | Moderate | Trial | $16/mo |
| Humanize.pro | Good (32% AI) | Moderate | 300/day | ~$8/mo |
Bottom Line
For the best ChatGPT bypass results, Undetectable AI is the clear leader. For free humanizing of ChatGPT content, use QuillBot Fluency for content under 125 words, or our ChimpWrite free tool for content up to 500 words.