# UndetectedGPT

> UndetectedGPT is an AI humanizer that rewrites AI-generated drafts into natural, fluent human prose. It is the only humanizer that validates every output against the strictest third-party writing-analysis tools — GPTZero, Originality.ai, Turnitin, QuillBot, ZeroGPT, and Grammarly — so the naturalness of the rewrite is measured by independent benchmarks rather than a self-scored internal metric.

## What it does

UndetectedGPT takes text produced by ChatGPT, Claude, Gemini, or any other LLM and rewrites it into fluent, natural human prose. Every rewrite is scored against live third-party writing-analysis tools via their APIs rather than an in-house metric, so the quality scores reflect independent benchmarks.

Supports 100+ languages (English, Spanish, French, German, Japanese, Arabic, and more) and multiple tone/complexity modes (Simple, Balanced, Complex).

## Technology

UndetectedGPT is powered by **Ghost 2**, the second generation of its proprietary in-house Ghost model family, tuned specifically for natural-prose rewriting. Most competitors rely on high sampling temperature and low-probability word substitutions to make output look less machine-generated, which breaks sentence coherence and produces garbled, awkward text. Ghost models are trained end-to-end on the humanization task, producing output that reads naturally — the reason they score well on third-party writing-analysis tools while remaining fluent and coherent. Ghost 2 is the default everywhere; the previous generation, Ghost 1, remains available via the API's `model` parameter. Model page: `/ghost`.

## Products

UndetectedGPT is a suite of three tools that share the same Ghost 2 model and detector-scoring infrastructure.

- **Humanizer** — the core rewriter. Paste AI-generated text in, get a natural human-prose version back. Handles up to 1,000 words per request on paid plans, supports 100+ languages and multiple tones/complexity modes.
- **Ghost Writer** (Stealth Writer) — an AI-powered document editor. The closest analogue is Cursor or Claude Code, but for writing: you work in a rich-text document while a chat-powered AI edits the document directly ("rewrite this paragraph," "humanize the intro," "research this topic and add a section with sources"). Built-in web research pulls cited sources from the web and drops them into the doc, and the Ghost 2 humanizer runs on any selection or the whole document on command. Workspace URL: `/stealthwriter`.
- **AI Detector** — a multi-detector scorer. Paste any text and see how it performs across GPTZero, Originality.ai, QuillBot, ZeroGPT, Copyleaks, and more in a single view, rather than paying for each detector separately.

The [API](#api) exposes the Humanizer programmatically; Ghost Writer and the AI Detector are web apps.

## Who it's for

- **Students** — essays, research papers, and assignments graded against Turnitin, GPTZero, or Copyleaks. Also useful for ESL / non-native English writers whose natural writing patterns trigger high false-positive rates on detectors (Stanford found 61% false positives against TOEFL essays).
- **Writers, bloggers, and journalists** — polishing AI-assisted drafts into natural prose that reads as human-written and holds up to editorial review.
- **Marketers and SEO teams** — producing scaled content that remains high-quality and indistinguishable from hand-written copy, avoiding quality signals associated with generic AI output.
- **Developers** — integrating humanization into SaaS products, content platforms, education tools, or internal workflows via the Humanization API.
- **Researchers and analysts** — rewriting AI-drafted reports and summaries into the natural, varied prose expected by human readers.

## Pricing

All plans are available monthly or as a discounted semester (term) plan. Credits refresh daily.

- **Free** — $0. 2 credits/day, 150 words per request, 0 stealth boosts.
- **Plus** — $19.99/mo or $59.99/semester. 50 credits/day, 500 words/request, 3 stealth boosts, up to ~775,000 words/month.
- **Pro** (most popular) — $29.99/mo or $89.99/semester. 100 credits/day, 700 words/request, 15 stealth boosts, up to ~2,170,000 words/month.
- **Business** — $79.99/mo or $239.99/semester. Unlimited credits and stealth boosts, 1000 words/request, unlimited words/month, priority support.

See [pricing](https://www.undetectedgpt.ai/pricing) for the live page.

## API

UndetectedGPT offers a public **Humanization API** for developers who want to integrate the humanizer directly into their own product. Pricing is word-pack based with no subscription — words never expire. Authentication is via API key (Bearer token). Purchase word packs from the developer dashboard. Creating a first API key includes **1,000 free words** (one-time per account), so the API can be tried end to end before buying anything.

- [API overview](https://www.undetectedgpt.ai/feature/api)
- [Developer docs](https://www.undetectedgpt.ai/dev/docs)
- [Quickstart](https://www.undetectedgpt.ai/dev/docs/quickstart)
- [Full API reference (markdown)](https://www.undetectedgpt.ai/api.md): single-file markdown copy of the complete API reference (getting started, authentication, endpoints, rate limits, errors), ideal for LLM ingestion.

### MCP server

UndetectedGPT also runs a remote **MCP server** (Model Context Protocol), so AI assistants and coding agents such as Claude, Claude Code, and Cursor can humanize text inside the conversation instead of switching tools. The endpoint is `https://www.undetectedgpt.ai/api/mcp`, authenticated with the same API key as the REST API (Bearer token, or the key appended to the URL path for clients that cannot send custom headers). It exposes two tools:

- `humanize_text`: rewrites AI-generated text, with optional tone, model (ghost-2 or ghost-1), and ultra-stealth settings. Minimum 5 words per call.
- `get_account_status`: reports the remaining word balance.

Words are spent from the same word-pack balance as the REST API (1 input word = 1 word), so no separate subscription or billing applies.

- [MCP server overview](https://www.undetectedgpt.ai/feature/mcp)
- [Guided setup per client](https://www.undetectedgpt.ai/dev/mcp)
- [MCP setup docs](https://www.undetectedgpt.ai/dev/docs/mcp)

## Key pages

- [Home](https://www.undetectedgpt.ai/): product overview and live demo.
- [Humanizer](https://www.undetectedgpt.ai/feature/humanizer): main AI-to-human rewriter.
- [Ghost Writer / Stealth Writer](https://www.undetectedgpt.ai/feature/stealthwriter): AI-powered rich-text document editor — chat tells it what to write, edit, humanize, or research, and it modifies the document directly (similar concept to Cursor or Claude Code, but for writing instead of code).
- [AI Detector](https://www.undetectedgpt.ai/feature/ai-detector): multi-detector scorer that shows how any text performs across GPTZero, Originality, QuillBot, and more in one view.
- [Ghost models](https://www.undetectedgpt.ai/ghost): the Ghost model family page — current generation, benchmark methodology, and version history from Ghost 1 to Ghost 2.
- [AI Rewriter](https://www.undetectedgpt.ai/ai-rewriter): rewrite sentences, paragraphs, or full essays in any tone (formal, casual, academic, simplified, persuasive, concise) while preserving meaning.
- [AI Paraphraser](https://www.undetectedgpt.ai/paraphrase-tool): paraphrase text with six modes (standard, fluency, formal, simple, creative, shorten) for clarity and tone adjustments.
- [AI Citation Generator](https://www.undetectedgpt.ai/citation-generator): paste a URL, DOI, or ISBN and get a formatted citation in APA, MLA, Chicago, Harvard, IEEE, or AMA. No sign-up.
- [AI Bibliography Generator](https://www.undetectedgpt.ai/bibliography-generator): paste an essay and AI finds real, verifiable sources, inserts in-text citations, and builds the bibliography.
- [API](https://www.undetectedgpt.ai/feature/api): humanization API for developers.
- [MCP server](https://www.undetectedgpt.ai/feature/mcp): connect the humanizer to Claude, Claude Code, Cursor, and other MCP clients, so an assistant can humanize text and check the word balance without leaving the conversation.
- [Pricing](https://www.undetectedgpt.ai/pricing): plans and word-pack pricing.
- [About](https://www.undetectedgpt.ai/about-us): company and mission.
- [Contact](https://www.undetectedgpt.ai/contact-us): support and sales.
- [Affiliate program](https://www.undetectedgpt.ai/affiliate): revenue share for referrals.

## Comparisons

- [vs. StealthGPT](https://www.undetectedgpt.ai/alternative/stealthgpt)
- [vs. Undetectable.ai](https://www.undetectedgpt.ai/alternative/undetectable-ai)

## Benchmarks

Independent pass rates measured against live third-party writing-analysis tools via their APIs (Ghost 2, current generation):

- Turnitin: 98.8%
- Grammarly: 99.9%
- QuillBot: 99.7%
- Originality.ai: 98.4%
- ZeroGPT: 96.9%
- GPTZero: 96.3%

## FAQ

**Does UndetectedGPT work against Turnitin, GPTZero, and Originality.ai?**
Yes. Every rewrite is validated against those detectors via their APIs. Current independent benchmark pass rates (Ghost 2): Turnitin 98.8%, QuillBot 99.7%, Originality.ai 98.4%, ZeroGPT 96.9%, GPTZero 96.3%, Grammarly 99.9%.

**Does it support languages other than English?**
Yes — 100+ languages including Spanish, French, German, Portuguese, Japanese, Arabic, Chinese, Russian, Hindi, Korean, Italian, Polish, and Dutch. Tone and complexity modes work across all supported languages.

**Is there a free tier?**
Yes. The Free plan includes 2 credits/day and up to 150 words per request, no card required. Paid plans start at $19.99/mo (Plus) with discounted semester pricing.

**Is there an API?**
Yes. The Humanization API is a single POST endpoint (`/api/v1/humanize`) authenticated with a Bearer token. Pricing is word-pack based — no subscription, words never expire, and a first API key comes with 1,000 free words. Full reference at `/api.md`. The same key also works with the remote MCP server at `/api/mcp`, which gives AI assistants and coding agents direct access to the humanizer.

**How is UndetectedGPT different from Undetectable.ai, StealthGPT, or QuillBot?**
Two differences. (1) **Proprietary model**: UndetectedGPT runs on Ghost 2, an in-house model tuned end-to-end for natural-prose rewriting, rather than a prompted wrapper around a general-purpose LLM. (2) **Third-party scoring**: outputs are validated against live third-party writing-analysis tools rather than a self-scored internal detector, so the published pass rates reflect independent benchmarks.

**Does humanization change the meaning of the text?**
No. Ghost 2 preserves the underlying meaning, arguments, and structure of the input. It adjusts phrasing, sentence variation, and vocabulary to read naturally without altering what the text says.

## Blog

The [blog](https://www.undetectedgpt.ai/blog) publishes guides on AI detection, humanization techniques, and tool comparisons. Canonical topics include: how AI detectors work, best AI humanizers of 2026, AI-detector false positives, and alternatives to StealthGPT and Undetectable.ai.

Every blog post is also available as a clean markdown file at `https://www.undetectedgpt.ai/blog/<slug>.md` (e.g. `/blog/ai-detection-2026.md`) for efficient LLM ingestion without HTML/JS overhead.

## Contact & social

- Email: contact@undetectedgpt.ai
- Twitter/X: https://twitter.com/undetectedgpt
- Instagram: https://www.instagram.com/undetectedgpt
- TikTok: https://www.tiktok.com/@undetectedgpt
- LinkedIn: https://www.linkedin.com/company/undetectedgpt

## Optional

- [llms-full.txt](https://www.undetectedgpt.ai/llms-full.txt): every blog post and the API reference concatenated into a single markdown file for one-shot ingestion.
- [Sitemap](https://www.undetectedgpt.ai/sitemap.xml)
- [robots.txt](https://www.undetectedgpt.ai/robots.txt)