Check if text was written by AI or a human
Enter text on the left and run the tool to see results here.
AI detector tool online with PDFPilot4U — instantly check whether any text was written by AI (ChatGPT, Claude, Gemini, etc.) or by a human, with confidence scores and sentence-level breakdowns. The AI detector uses Claude Sonnet 4.5 trained on AI vs human writing patterns to spot telltale signals like vocabulary uniformity, sentence-length cadence, transition word overuse, and stylistic flatness. Perfect for educators screening student essays, editors verifying freelance submissions, recruiters checking AI-assisted cover letters, or publishers vetting article submissions. The AI detector provides a percentage AI-probability score plus a sentence-by-sentence highlight showing exactly which passages look AI-generated and which look human. Supports 50+ languages with the same accuracy. Free for 3 detections per day on guest accounts, 50 on Pro, unlimited on Business. Text is processed privately, auto-deleted in 24 hours, never used to train AI.
Paste text into the editor, or upload a PDF/.docx. The AI detector handles up to 10,000 words per scan.
Click Detect — analysis completes in 5-15 seconds with AI probability score and sentence-level highlights.
See AI-probability per sentence color-coded. Export the report as PDF for record-keeping.
Teachers run essays through the AI detector to flag suspected AI-generated submissions for academic integrity review.
Editors check freelance article submissions to ensure original human writing, not AI-assisted output.
Recruiters scan candidate cover letters to identify generic AI-generated text vs personalized human writing.
How AI Detector on PDFPilot4U compares to the most common alternatives.
| Feature | PDFPilot4U | iLovePDF | Smallpdf |
|---|---|---|---|
| Detection accuracy | 95-98% | No AI detector | No AI detector |
| Sentence-level breakdown | Color-coded per sentence | N/A | N/A |
| Languages supported | 50+ | N/A | N/A |
| Free daily limit | 30 operations/day (guest), unlimited on Business | ~3 tasks/hour for free, premium starts $7/mo | 2 documents/day free, premium $9/mo |
| Max file size (free) | 5 MB free, 100 MB Pro, 500 MB Business | ~10 MB free | ~5 MB free |
| AI features included | 12 AI tools (Ask PDF, Summarize, Translate, etc.) | Limited — AI add-on only on premium | AI features locked behind premium tier |
| Privacy / data handling | TLS 1.3 + AES-256, auto-delete in 24h, no model training | Files deleted in 2h, standard SSL | Files deleted in 1h, ISO 27001 |
| No watermark on output | Always — free + paid | Free tier may add watermark | Free tier may add watermark |
The AI detector achieves 95-98% accuracy on benchmark datasets, with sentence-level resolution. Very short texts (<200 words) have lower accuracy due to limited sample size.
Yes. The detector identifies text from major LLMs including ChatGPT (3.5/4/4o), Claude (Sonnet/Opus), Gemini, Llama, and Mistral models.
Sophisticated humanization (like our Humanize tool) can reduce detection rates, but skilled detectors still catch ~70% of humanized content. Check both tools for context.
Yes. The AI detector supports 50+ languages with consistent accuracy across major languages.
The detector analyzes statistical patterns (vocabulary entropy, sentence-length variance, perplexity, transition usage) that differ between AI and human writing.
False positives occur ~2-5% of the time, especially on formulaic writing (legal templates, technical docs). Always review flagged content manually before acting.
No. Text is analyzed in-memory and auto-deleted within 24 hours. We never train models on user data.
3 scans per day on guest and free accounts. Pro gets 50/day, Business unlimited. No credit card for any tier.
Scans your text and corrects grammatical errors and writing mistakes.
Translates your PDF content into another language while keeping formatting.
Rewrites AI-generated content to sound natural and human.
Ask questions and get instant answers from your PDF content.
