GPTZero tells you if it's AI. Credify tells you where the patterns are. A 5-signal ensemble: dual-path neural classifier, AI phrase density, perplexity, burstiness, and repetition: scores every sentence so you know exactly what to address.
Four signals on the casual path, five on the academic one, combined with fixed weights so no single model makes the call. The weights below were set by hand from testing, not learned from a labelled benchmark.
Dual-path routing between two third-party classifiers we did not train: casual text goes to a general-purpose AI detector, academic text (citation markers detected) to one trained on human vs AI research abstracts. Both score in 500-token chunks. Their training sets lean towards earlier AI writing, which is the main limit on this tool.
Counts scholarly GPT flourishes per 100 words: "delve into", "it is worth noting", "plays a crucial role", "multifaceted", "transformative" and similar. AI-drafted academic prose tends to lean on them noticeably harder than human researchers do, which is why this signal only applies on the academic path.
Measures how predictable the full document is to a language model. AI text scores low perplexity (very predictable); natural human writing is less predictable. Measured against a conversational baseline.
Scores every sentence with a local language model and measures the variance. AI text is uniformly predictable: low variance. Human writing is bursty: some sentences are simple, others complex. High variance = likely human.
Counts repeated 3-word phrases across the text. AI outputs over-reuse common patterns even when paraphrasing.
Paste text, enter a URL, or upload a PDF/DOCX.
Each signal scores your text independently.
Signals combined by weight → 0–100% AI probability + confidence level.
Every sentence scored separately so you see exactly which parts read as AI.
High score? Use the E‑E‑A‑T Checker to rewrite with human signals.
We used to run a feature table here comparing Credify against GPTZero and Originality.ai. It came down, because we could not keep it honest: those are actively developed commercial products, we have not benchmarked against them, and a stale table asserting what a competitor cannot do is marketing rather than information. Here is what is true about this tool instead.
| This AI detector | Where it stands |
|---|---|
| Detection method | Four to five weighted signals, depending on whether the text routes to the casual or academic path |
| Models used | Two third-party classifiers we did not train, plus a small language model for perplexity scoring |
| Accuracy | No published figure — we have not run a benchmark we would stand behind |
| Per-sentence scoring | Yes, with the full signal breakdown and a High/Medium/Low confidence label |
| Weakest on | Newest-generation AI text, formal or technical human writing, and anything under ~300 words |
| Cost | Free, no signup, no credit card. A fair-use rate limit applies |
| After detection | E-E-A-T scoring and a rewrite tool on the same site, which is the part genuinely worth staying for |
A single “AI” or “Human” verdict is the least useful thing an AI detector can give you, because it hides how sure it actually is. This free AI detector returns a 0–100% likelihood with sentence-level breakdowns instead, so you can see which parts of your content read as AI-generated and which read as human, and disagree with it where it looks wrong. The dual-path classifier routes casual and academic text separately, which is aimed at cutting false positives on formal writing — a real weak spot for AI detectors generally, including this one.
SEO teams use this AI detector to audit AI-assisted content before publishing. Editors use it to check writer submissions without relying on a single-model verdict. Students use the AI detector to verify their own writing won't be falsely flagged by institutional tools. Teachers use it to distinguish between AI-generated and student-authored work at the sentence level: not just the document level.
After running this AI detector, use the AI Humanizer to rewrite flagged sections, paste the content into the E-E-A-T Checker to score quality signals, check sentence structure with the readability checker, and remove passive-voice patterns that this AI detector flags as high-probability AI signals with the passive voice remover.
Detect, humanize, and verify: run the full AI content workflow.
Free, no signup, no limits. 5-signal ensemble detection with sentence-level breakdown and a direct path to the fix.