AI Text Detector
Paste any passage of text to estimate how likely it was generated by AI. You'll get a clear 0–100 score and sentence-level highlights showing where the AI signals are strongest.
It's free and works on any text — essays, messages, descriptions, or snippets. As with all AI detectors, treat the result as guidance rather than a definitive answer (how accurate are they?).
How AI text detection works — perplexity and burstiness
Two ideas do most of the work. The first is predictability (researchers call it perplexity). A language model is a next-word-guessing machine, so the text it produces is full of words that are easy to predict from what came before. Human writing surprises more often — odd word choices, sudden turns. The second is variation between sentences (burstiness): people alternate short punchy sentences with long winding ones, while AI keeps length and structure unusually even. This detector measures both signals sentence by sentence and combines them into your 0–100 score (full explanation).
Reading the result by text type
Blog posts and reviews: human writing carries lived detail — prices, dates, complaints. Smooth generalities with stacked adjectives push the score up. Reports and coursework: formal register makes false positives more likely here; look at the highlighted sentences rather than the total, and check whether they contain real data and examples. News-style copy: already formulaic, so human-written text can score somewhat high — paste several paragraphs together for a fairer read. Short messages: under 100 characters there's simply not enough signal; treat those scores as rough hints.
Because the same text always returns the same score, you can revise flagged sentences and re-check to see exactly how much your edits changed the signal.
Why your own writing can get flagged
The detector measures how predictable and uniform a text is — and carefully polished human writing, especially formal documents, can look statistically similar to AI output. Varying sentence length and adding details only you could know usually brings the score down. The flip side: this is exactly why a detector score can never prove misconduct. Use it to improve a text, not to judge a person (why detectors flag human writing).
Frequently asked questions
How does the AI text detector work?+
It analyzes statistical patterns in the text — predictability and variation across sentences — to estimate the probability that it was machine-generated.
Is an AI text detector the same as an AI checker?+
Yes — AI text detector, AI checker, and AI writing detector all describe the same task: estimating whether a passage was machine-generated. This page handles all of them.
What's the minimum text length?+
Short snippets are unreliable. Aim for at least 100 characters (roughly 15+ words); below that, scores are pulled toward the middle.
Why does my own writing get flagged as AI?+
The detector measures predictability and uniformity, and polished formal writing can look statistically similar to AI output. Varying sentence rhythm and adding concrete personal detail usually lowers the score.
Is my text stored?+
Text is used only to produce your result and is not saved without consent. Avoid pasting sensitive personal information.
⚠️ Disclaimer: AI Killer results are probabilistic signals and are not 100% accurate. Detectors can flag human writing as AI, so do not use this as the sole basis for accusations of plagiarism, cheating, or academic misconduct.