# QuillBotAI Pro — Free AI Text Detector & SynthID Watermark Scanner

> Free, unlimited AI content detection tool with sentence-level perplexity scoring, burstiness variance analysis, and Google SynthID watermark verification. No signup. No data retention. GDPR & CCPA compliant.

QuillBotAI Pro is a free, browser-based AI text detector. It identifies AI-generated content from GPT-4o, GPT-5, Claude, Gemini, Llama, Mistral, and humanizer-altered text. It also detects Google SynthID watermarks in images and videos. All processing runs in volatile memory — zero data retention, no accounts required.

## Docs

- [AI Text Detector](https://www.quillbotai.pro/): Paste any text to receive a sentence-level AI confidence heatmap, perplexity score, burstiness variance, and a built-in humanizer bypass.
- [SynthID Watermark Detector](https://www.quillbotai.pro/synthid): Upload images (JPEG, PNG, WebP) or videos (MP4, WebM) up to 22 MB to detect Google SynthID and other generative watermarks.
- [Sitemap](https://www.quillbotai.pro/sitemap.xml): Full sitemap of all pages.

## API

- [AI Detection Endpoint](https://www.quillbotai.pro/api/detect): POST JSON with a `text` field. Returns `overallAIScore`, `overallHumanScore`, per-sentence scores with alerts, perplexity/burstiness metrics, and a humanized version.
- [SynthID Detection Endpoint](https://www.quillbotai.pro/api/detect-synthid): POST JSON with `media` (base64), `mimeType`, and `filename`. Returns `isWatermarked`, `confidenceScore`, source model, and forensic breakdown.

## Detection Capabilities

- Supported languages: English (EN-US, EN-GB, EN-CA, EN-AU), Urdu (Nastaliq), Roman Urdu, Hindi, Spanish, French, German, Portuguese.
- Benchmark accuracy: 99.8% on AIDEF 2025/2026 datasets for texts over 100 words.
- False positive rate: <0.4% on non-native English corpora.
- Detection vectors: perplexity matrix, burstiness variance (σ²), vocabulary diversity index, model-specific distribution fingerprinting.
- Detects humanizer-bypassed and paraphrased AI text via residual probability distribution analysis.

## Privacy

- Zero-retention: all text and media processed in volatile memory, purged immediately after analysis.
- No logs, no databases, no training data collection.
- Fully GDPR and CCPA compliant.

## Optional

- [robots.txt](https://www.quillbotai.pro/robots.txt): Crawler access rules.
- [Privacy Policy](https://www.quillbotai.pro/privacy): Full privacy and data handling policy.