Claude AI detector with sentence-level evidence
Claude's writing is among the most natural of any assistant, which makes it harder to spot by eye. Paste the text here to see how it scores and which sentences carry the strongest signal.
0 / 1,500 words
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Why Claude text is harder to recognise by reading
Readers often describe Claude's prose as less formulaic than other assistants': fewer stock openers, more varied sentence length, a more conversational register. That means the surface habits people have learned to look for are less reliable here, and a text can read as natural while still scoring high.
A detection model works from the statistics of word choice across the whole passage, not from a checklist of phrases, so it can register a signal where the pattern list finds little. When that happens the report says so plainly: flagged on statistical pattern, no specific marker.
Habits that do show up
Claude has tendencies of its own. Dashes used for asides. Balanced “not this, but that” constructions. Careful hedging and qualifications. Tidy closing lines that restate the point. The phrasing and lists-of-three signals pick up some of these; the rest show up only in the score.
Longer samples help most here
Because the signal is subtler, short samples of Claude text are the most likely to come back Uncertain. Check 300 words or more where you can, and prefer the original output over a version that has been pasted through other tools.
How the AI detector works
An AI detector is a classifier that estimates the probability that text was written by a language model rather than a person. It works by measuring statistical patterns in the writing, not by tracing where the text came from.
Give it something to read
Paste text, drop in a PDF or Word file, or enter the address of a web page. Documents are opened in your browser, so the file itself never leaves your device.
The text is scored
A detection model trained on human writing and on output from AI systems rates the whole text and each sentence for how closely it matches machine writing.
You see the evidence
The report marks every sentence, lists the writing patterns found, and tells you how much confidence the result deserves.
How accurate is AI detection, honestly?
AI detection is accurate enough to raise a question, but not accurate enough to prove an answer. The best detectors catch most unedited AI text with few false alarms, but accuracy drops sharply when text is paraphrased, lightly edited, or written by a non-native English speaker.
Key takeaways
- Accuracy claims of 99% come from the vendors’ own benchmarks.
- One 2026 test of five detectors put the top two at 72% and 74% overall accuracy.
- False positives fall hardest on non-native English writers.
- A score is a probability estimate, not evidence of misconduct.
Reading the score
| Score | Verdict |
|---|---|
| 0–14 | Human-writtenLittle or nothing resembles AI writing. |
| 15–34 | Likely human-writtenMostly reads as a person, with a few AI-like passages. |
| 35–69 | UncertainMixed signals. Not evidence either way. |
| 70–89 | Likely AI-generatedMostly reads as AI, possibly edited by a person. |
| 90–100 | AI-generatedStrong, consistent AI signals throughout. |
A score in the Uncertain range is reported as Mixed when the sentences back that up, with at least 25% of the words in AI-like sentences and at least 25% in human-like ones.
Supported languages: English, French, Spanish, Portuguese, German, Dutch, Polish, Romanian, Italian and Simplified Chinese.
Claude AI Detector: common questions
Is Claude harder to detect than ChatGPT?
By eye, many readers find it so. For a detection model the difference is smaller, but results vary by topic, length and how the text was prompted. The confidence level on each result is the best guide.
Does the detector name the model that wrote the text?
No. It reports the likelihood that an AI model wrote the text, not which one.
What if Claude only edited my writing?
Light editing usually leaves your voice intact and the score low. If you asked Claude to rewrite or “improve” whole passages, those passages are Claude's writing and may be highlighted.
Can I check a Claude-written document?
Yes. Upload a PDF, Word or text file from the File tab; it is read in your browser and only the text is analysed.