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.
💡 Troubleshooting? See our comprehensive troubleshooting guide for common issues and solutions.
StealthHumanizer now ships an initial command-line interface for local humanization and detector checks.
# Run without installing a global binary
npm run cli -- detect --text "Furthermore, it is important to note that..."
# Humanize from stdin with the Gemini provider
export GEMINI_API_KEY="your-key"
echo "Draft text..." | npm run cli -- humanize --model gemini --level medium
# Read and write files
npm run cli -- humanize --input draft.txt --output humanized.txt --style academicThe package exposes both stealthhumanizer and stealth-humanize binaries
when built or linked:
npm run cli:build
npm link
stealthhumanizer providersUseful commands:
humanize- runs the full multi-pass rewriting pipelinedetect- scores text with the built-in AI-signal detector, no API key neededproviders- lists provider ids, default models, and API key environment variables
Run npm run cli -- --help for the full option list.
Two providers run a local CLI you already have logged in, as a subprocess, instead of calling an HTTP API. They use the binary's own auth, so no API key is required:
# Uses your local Claude Code login
stealthhumanizer humanize --model claude-code -i draft.txt
# Uses your local OpenAI Codex login
echo "Draft text..." | stealthhumanizer humanize --model codex--model claude-codespawns your localclaudeCLI (Claude Code)--model codexspawns your localcodexCLI (OpenAI Codex)- Point at a non-default binary with
STEALTHHUMANIZER_CLAUDE_CODE_BINorSTEALTHHUMANIZER_CODEX_BIN - CLI-only: these are skipped by auto-selection and are not available in the browser or serverless runtimes (they spawn a subprocess). The web API rejects them (including in model chains) so a browser user can't make a self-hosted server spawn its logged-in CLI.
Security note — untrusted input. The text being humanized is treated as untrusted (it can contain prompt-injection). The runners are confined so an injected instruction can't make the agent act:
claude-coderuns with--tools "", which fully disables all tools — it cannot read/write files or run commands. Preferred for untrusted input.codexhas no "disable all tools" switch, so it is confined as tightly as the platform allows:--sandbox read-only(no writes/network), an isolated empty working directory, and no inherited environment. A determined injection could still read absolute paths via a read-only command, so preferclaude-codewhen the input is fully untrusted.
Run npm run test:cli to build the packaged CLI entry point and execute the
CLI regression suite.
This walkthrough is specifically for the Groq (Free) provider flow.
-
Open Settings, then go to Danger Zone and clear old keys if you want a clean reset.
-
In provider selection, choose Groq (FREE).
-
In the Groq settings card, click Get API Key.
-
In Groq Console, create a key (set name + expiration setting).
-
Copy the generated Groq key (usually visible once).
-
Paste it into StealthHumanizer’s Groq API key field and press Save.
-
Click Test Key and confirm the key is valid.
-
Return to provider selection and keep Groq (Free) active.
-
Configure Humanizer options (rewrite level, style, tone, target score, max words).
-
Paste/upload your text and run the pipeline.
-
Review output, re-humanize if needed, and export.
Safety note: Never share API keys in public chats, screenshots, repos, or screen recordings. To remove stored keys, use Settings → Danger Zone → Clear All API Keys.
| 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 (
stealthhumanizer, initial local/package binary) - 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:
QuillBot alternative, Undetectable.ai alternative, StealthWriter alternative, Hix Bypass alternative, Bypass AI detection, AI humanizer free, Humanize AI text free, Free AI detector bypass, Open source AI humanizer, GPTZero bypass, Turnitin bypass, AI text rewriter free, Make AI text undetectable, AI to human text converter
MIT License © 2024 Rudra Sarker. Free for personal and commercial use.
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