How Our AI Content Detector Works: 14 Statistical Signals
Unlike server-based detectors that send your text to a third party, our free AI content detector runs 14 statistical signals entirely in your browser. Nothing is uploaded, stored, or transmitted. Here is what the tool measures when you click "Check for AI":
- Sentence length uniformity — AI writing tends toward unnaturally even sentence lengths; human writing varies.
- AI cliché phrases — scans against 80+ phrases overused by large language models (e.g. "delve", "in today's fast-paced world").
- Missing contractions — AI text underuses contractions like "don't" and "can't".
- Flat punctuation — detects monotonous comma/period patterns with little expressive punctuation.
- Repetitive sentence openers — flags paragraphs that start the same way again and again.
- Vocabulary diversity — measures type-token ratio; AI text is often lexically narrower than human writing.
- Burstiness — human writing mixes short punchy sentences with long ones; AI is metronomic.
- Transition word density — overuse of "furthermore", "moreover", "additionally" is a classic AI tell.
- Perplexity proxy — estimates how "predictable" word choices are; low unpredictability suggests AI.
- Hedging language — counts qualifiers like "it is important to note" that models lean on.
- Listicle formatting — excessive bullet-point structuring is common in raw model output.
- Pronoun distribution — AI underuses first-person voice compared to human authors.
- Adverb density — inflated use of "-ly" adverbs correlates with generated text.
- Conclusion templates — detects formulaic closers like "in conclusion" and "overall".
Each signal is weighted by reliability and combined into a single Human Score with a confidence level. Treat scores as guidance, not proof — no detector is 100% accurate, including ours. See our about page for the full methodology notes. Last updated: October 2026.
Free AI Detector vs Paid Tools: Honest Comparison
How do we compare against the big names? Here is an honest breakdown:
| Feature | Free AI Content Detector | GPTZero | Originality.ai |
|---|---|---|---|
| Price | 100% free | Free tier + paid plans | Paid (per-word credits) |
| Signup required | No | Yes for full features | Yes |
| Your text sent to a server | Never — 100% in-browser | Yes | Yes |
| Detection method | 14 statistical signals | ML model | ML model |
| Extra writing tools | 6 included free | Limited | Paid add-ons |
Paid ML-based detectors can be more accurate on heavily edited text. Our advantage is simple: free, instant, and private — ideal for quick checks where you don't want to create an account or upload sensitive writing.
Free Writing Tools Included
Every tool below runs entirely in your browser — no signup, no uploads:
- Readability Checker — 6 formulas (Flesch-Kincaid, Gunning Fog & more)
- Keyword Density Checker — find stuffing before Google does
- Word Counter — words, characters, sentences, reading time
- Tone Analyzer — formal vs casual vs confident
- Plagiarism Checker — compare two texts for overlap
- Text Summarizer — extractive summaries instantly