Free, open-source AI text humanizer. No login. No limits.
Transform AI-generated text into natural, human-like writing using multi-pass rewriting, style-aware processing, and statistical fingerprint disruption.
If this saves you money on paid humanizers, consider giving it a star -- it helps others find it.
Try it now: stealthhumanizer.vercel.app -- paste AI text, pick a free provider (Gemini), click humanize. Done.
AI detectors (GPTZero, Originality.ai, Turnitin) catch AI text through statistical fingerprints:
- Low perplexity — predictable, boring word choices
- Low burstiness — uniform sentence lengths
- AI-typical phrases — "furthermore," "it is important to note," "delve into"
- Rigid structure — same paragraph pattern throughout
StealthHumanizer disrupts all of these signals with a 4-layer pipeline that produces text reading like a real person wrote it.
| Feature | Description |
|---|---|
| 13 AI Providers | Gemini (free), OpenAI, Claude, Groq (free), Mistral, Cohere, Together, OpenRouter, Cerebras, DeepInfra, HuggingFace, Cloudflare, ZAI |
| 4 Rewrite Levels | Light (subtle fixes), Medium (natural rewrite), Aggressive (complete rewrite), Ninja (maximum stealth) |
| 6 Writing Styles | Humanize, Academic, Professional, Casual, Creative, Technical |
| 9 Text Purposes | Essay, Article, Blog, Email, Marketing, Report, Story, Social Media, General |
| 13 Tone Presets | Conversational, Journalistic, Persuasive, Storytelling, Humorous, Analytical, and more |
| Multi-Pass Ninja Mode | Auto-refinement loop targeting 90%+ human score |
| Style-Aware Processing | Post-processing adapts to academic vs casual context |
| AI Detection Scoring | 12-metric analysis with confidence intervals and detailed reports |
| File Upload | Paste text or upload PDF/DOCX files |
| Grammar Check | Built-in grammar and spell checking |
| 16+ Languages | English, Chinese (Simplified + Traditional), Spanish, French, German, Japanese, Korean, Arabic, Hindi, and more |
| Batch Processing | Humanize multiple texts at once |
| Export | Download as TXT, DOCX, or PDF |
| 100% Private | API keys stored in your browser only. No server-side data storage. |
Input Text → Layer 1: LLM Rewrite → Layer 2: Post-Processing → Layer 3: Multi-Model Chain → Layer 4: Final Polish → Output
Layer 1 — LLM Rewrite: Your chosen AI provider rewrites the text using anti-detection prompts that enforce burstiness, perplexity injection, and structural disruption.
Layer 2 — Non-LLM Post-Processing: 500+ synonym swaps, 230+ collocation replacements, AI vocabulary removal, sentence length manipulation, typographic variation. Style-aware — academic text stays formal, casual text gets personality.
Layer 3 — Multi-Model Chain (Optional): Pass text through multiple AI providers to mix statistical fingerprints. Each model adds different patterns.
Layer 4 — Final Polish: Light cleanup pass. Readability guard ensures quality doesn't degrade.
The built-in detector analyzes:
- Perplexity (word choice unpredictability)
- Burstiness (sentence length variation)
- Vocabulary diversity
- AI phrase density
- Passive voice ratio
- Transition word frequency
- Sentence start diversity
- Hedging language
- Quantifier overuse
- Pronoun usage patterns
git clone https://github.com/rudra496/StealthHumanizer.git
cd StealthHumanizer
npm install
npm run devOpen http://localhost:3000 and add your API key in Settings. Gemini is free — get a key at Google AI Studio.
Or use it live at stealthhumanizer.vercel.app.
| StealthHumanizer | QuillBot | StealthWriter | Undetectable.ai | |
|---|---|---|---|---|
| Price | Free | $9.99/mo | $19/mo | $14.99/mo |
| Open Source | Yes (MIT) | No | No | No |
| AI Providers | 13 | 1 | 1 | 1 |
| No Login Required | Yes | No | No | No |
| Data Privacy | Browser-only keys | Server-side | Server-side | Server-side |
| Multi-Language | 16+ | Limited | English only | English only |
| Purpose Selector | 9 purposes | No | No | No |
| Style Presets | 6 styles | 4 modes | 3 modes | 3 modes |
| Tone Options | 13 tones | 2 modes | No | No |
| File Upload | PDF, DOCX | No | No | No |
| Batch Processing | Yes | No | No | No |
| Grammar Check | Built-in | Separate tool | No | No |
| Custom Writing Sample | Yes | No | No | No |
| Self-Hostable | Yes | No | No | No |
stealthhumanizer/
├── app/ # Next.js app router
│ ├── api/ # API routes (humanize, detect, grammar, upload)
│ ├── layout.tsx # Root layout with SEO + structured data
│ └── page.tsx # Main page
├── components/ # React components
│ ├── Humanizer.tsx # Main humanizer UI
│ ├── BatchHumanizer.tsx # Batch processing UI
│ ├── Detector.tsx # Standalone detector UI
│ ├── Settings.tsx # API key management
│ └── Navbar.tsx # Navigation
├── lib/ # Core logic
│ ├── detector.ts # 12-metric AI detection engine
│ ├── prompts.ts # Anti-detection prompt system (EN + ZH)
│ ├── postprocess.ts # Non-LLM post-processing engine
│ ├── providers.ts # 13 AI provider integrations
│ ├── readability.ts # Flesch, Kincaid, Coleman-Liau metrics
│ └── server/ # Server-side modules
│ ├── humanization-governance.ts # Safety + regression guard
│ ├── model-runtime.ts # Logistic regression scorer
│ └── text-utils.ts # Tokenization utilities
└── public/ # Static assets + style models
We love contributions! This is a community project and every PR helps.
Start with issues tagged good first issue — these are specifically scoped for new contributors.
- Fork the repository
- Create a feature branch:
git checkout -b feat/your-feature - Make your changes and test locally with
npm run dev - Commit with conventional style:
feat: add your feature - Push and open a Pull Request
Read CONTRIBUTING.md for full guidelines.
- Framework: Next.js 16 (App Router)
- Language: TypeScript
- Styling: Tailwind CSS 4
- Icons: Lucide React
- Charts: Recharts
- Deployment: Vercel
- Browser extension (Chrome/Firefox)
- CLI tool (
npx stealthhumanizer) - Fine-tuned local models for offline use
- Real detector benchmarking dashboard
- API service layer for programmatic access
- Collaborative editing with version history
Portfolio · GitHub · LinkedIn · Twitter/X
If you're searching for any of these, StealthHumanizer is the free, open-source alternative:
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MIT License © 2024 Rudra Sarker. Free for personal and commercial use.