Free AI Content Detector — Check Any Text Instantly
Paste any text and get an instant AI-detection score based on 6 statistical signals. No signup, no upload, no data stored. Works entirely in your browser.
What is the AI Content Detector?
An AI content detector analyzes written text to determine whether it was likely generated by an artificial intelligence model like ChatGPT, GPT-4, Claude, or other large language models. Unlike plagiarism checkers that compare text against a database of existing content, AI detectors look for statistical patterns that reveal the fingerprint of machine-generated writing. BACKR's detector runs entirely in your browser — your text never leaves your device, is never stored, and is never sent to a server. The analysis is instant because it uses lightweight heuristics rather than a heavy machine-learning model. This means you can check sensitive, confidential, or unpublished content without any privacy concerns. The tool examines six key signals that distinguish human writing from AI writing: burstiness (how much sentence length varies), vocabulary diversity (how varied the word choices are), AI phrase density (how many overused AI transition phrases appear), passive voice ratio, sentence start diversity, and average sentence length. Human writers naturally produce text with high burstiness — some sentences are short and punchy, others are long and complex. AI models tend to produce text with uniform sentence lengths and predictable word choices. The detector combines these signals into a single score from 0 to 100, where 100 means very human-like and 0 means very AI-generated. A score above 70 suggests human-written content, 40-70 indicates mixed or AI-assisted content, and below 40 suggests AI-generated content.
100% Private — No Data Upload
Your text is analyzed entirely in your browser. Nothing is sent to a server, stored, or logged. Safe for confidential and unpublished content.
6 Statistical Signals
Burstiness, vocabulary diversity, AI phrase density, passive voice, sentence start diversity, and average sentence length — the same signals used by professional detection tools.
Instant Results
No waiting for API calls or server processing. The heuristic engine runs in milliseconds directly in your browser.
Flagged AI Phrases
See exactly which AI-typical phrases were detected in your text — from 'furthermore' to 'delve into' to 'it is important to note' — so you can edit them out.
Deep Dive: How the 6-Signal Detector Works
Burstiness Analysis
Human writing naturally varies sentence length dramatically — short punchy fragments next to long complex sentences. AI models produce uniform sentence lengths with low standard deviation.
Vocabulary Diversity (TTR)
Type-Token Ratio measures how many unique words appear vs total words. Human writing scores 0.55-0.75 on 200+ word texts. AI tends toward 0.40-0.55 with predictable word choices.
AI Phrase Density
LLMs overuse certain transition phrases: furthermore, moreover, it is important to note, delve into. Each occurrence increases the AI probability score.
Passive Voice Detection
AI models overuse passive constructions (is powered by, was designed for). The detector counts be-verb + past participle patterns per sentence.
Sentence Start Diversity
Humans rarely start consecutive sentences with the same word. AI models often repeat starters (The, This, Additionally) creating detectable patterns.
Average Sentence Length
AI tends toward medium-length uniform sentences (12-18 words). Human writing has wider distribution including very short and very long sentences.
Who Uses the AI Content Detector?
Content Publishers
Verify that freelance writers deliver original human content, not AI-generated text.
SEO Professionals
Check if AI-assisted content will be flagged by Google algorithms before publishing.
Educators
Screen student submissions for AI-generated essays and assignments.