Free AI Content Detector

Paste any text to check it for AI writing patterns. Nine heuristic categories analyze vocabulary, sentence structure, and compression signals, all inside your browser.

Your text never leaves this page
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Optimized for English text · Minimum 30 words · Press Ctrl+Enter to analyze

Why this tool

Why use BrieferCopy's AI detector

Most AI detectors send your text to a remote server, run it through a proprietary neural network, and hand you a percentage. You have no idea what the model actually looked for. If it flags your writing, good luck figuring out why.

This tool is different. Every check runs in your browser using JavaScript. Your text is never sent to a server, API, or third party. Not even to us. The analysis happens on your machine and stays there.

The detector uses nine heuristic categories with documented criteria instead of a black-box ML model. You can expand each one to see exactly what it flagged and why. When your job is to fix the problems a detector finds, knowing what triggered the score matters more than the score itself.

No signup. No usage caps. No paywall hiding the detailed breakdown.

It is built for content teams doing a sanity check before publishing, writers who want to catch AI-sounding patterns in their drafts, and editors reviewing outside submissions. If you handle sensitive text like legal briefs, unpublished manuscripts, or internal comms, sending that content to a third-party server is probably off the table. This tool avoids that problem entirely.

Once you know what the detector flags, fixing it is the real work. Our guide on conversational copywriting covers how to write in a voice that sounds human, not generated.

The method

How AI detection works

AI-generated text leaves statistical fingerprints that differ from human writing in measurable ways.

Compression ratios tell you a lot. When you compress AI text alongside a corpus of known AI writing using deflate, the two compress together more efficiently than human text paired with the same corpus. This is the idea behind ZipPy, a research project from Thinkst Canary. The compression category here adapts that approach to run in the browser using the CompressionStream API.

Vocabulary is another giveaway. Large language models lean on certain words far more than human writers do. "Delve," "tapestry," "leverage," "synergy," "transformative" all appear in AI output at rates dozens of times higher than in published human text. The vocabulary category checks against a two-tier list: 54 strong AI indicators and 75+ moderate ones.

Then there is sentence rhythm. Human writing is bursty. Short punchy sentences sit next to long winding ones. AI tends to produce sentences that hover around the same length. The detector measures the coefficient of variation in sentence lengths and tracks how often consecutive sentences land at similar word counts.

Stock phrases are easy to spot once you know to look for them. "In today's digital landscape," "When it comes to," "Let's dive in." The formulaic patterns category checks for over 30 of these.

Four more categories round out the analysis: qualifier phrases ("It's important to note"), overused conjunctive adverbs ("However," "Furthermore," "Moreover"), excessive em dashes and semicolons, and repeated paragraph openings. All common in default AI output. All relatively rare in human drafts. If you are using AI as part of a blog automation workflow, these are the patterns to edit out before publishing.

Each category scores independently. When multiple categories agree, a concordance boost amplifies the overall result. Five independent signals pointing the same direction are harder to dismiss than any single one.

Getting started

How to use the AI content detector

Paste your text into the input area above. The detector handles any length but works best on 200+ words. Minimum is 30.

Click "Analyze Text" or press Ctrl+Enter (Cmd+Enter on Mac). Compression analysis takes a moment because it runs real deflate operations in the browser.

The overall score runs from 0% (likely human) to 100% (AI-generated), shown on a color-coded gauge. Under 15% suggests human writing. Above 55% suggests heavy AI involvement.

You can expand individual categories to see what each one caught. Every category shows a plain-language interpretation plus the raw stats behind the number.

The highlighted text view marks flagged words and phrases directly in your content, which makes it easier to find and revise specific problem areas. For practical advice on rewriting flagged sections, see our posts on writing web copy that sells and writing strong hook sentences.

What to expect

Accuracy and limitations

No AI detector is 100% reliable, heuristic or ML-based. This is a signal, not a verdict.

It works best on unedited AI output. Raw ChatGPT text will get caught. Heavily edited AI text, or text generated with constraints like "write in short, varied sentences; avoid transition words," will score lower.

Formal writing can trip false positives. Academic papers and legal documents use hedging language and transition words by convention. A 30% score on a research paper means something different than a 30% score on a blog post. Always read the category breakdowns, not just the headline number.

The tool catches patterns, not provenance. It identifies statistical tendencies common in AI output but cannot prove a specific LLM generated the text. Treat the results as one input alongside your own editorial judgment.

Longer text gives better results. Fifty words is a tiny sample. At 200+, the statistical categories have enough data to work with.

If you need ML-based detection with published accuracy studies, Originality.ai, GPTZero, and Copyleaks take a different approach. This tool is a free, private first pass rather than a replacement for paid detectors when the stakes are high.

For teams that want to use AI responsibly in their content process, our SEO content systems and blog systems include editorial checklists and quality gates that catch these patterns before they ship.

Your data

Privacy-first AI detection

Your text never leaves this page. That is how the tool is built, not a marketing line.

All nine detection categories run as JavaScript in your browser. Compression analysis uses the browser's native CompressionStream API. Vocabulary checks, pattern matching, and statistical calculations all run locally. Nothing hits the network during analysis.

You do not need an account. No cookies track what you analyze. Close the tab and the text is gone.

If you are reviewing pre-publication articles, legal documents, internal memos, or student work, you probably do not want that content sitting on someone else's server. It does not sit on ours, either. Read our privacy policy for details on how the rest of the site handles data.

Nine categories

What this tool detects

Each category scores independently. When multiple categories agree, a concordance boost amplifies the overall result.

compress

Compression Analysis

Compresses your text alongside a corpus of known AI writing using deflate. AI text shares predictable byte-level patterns, so the two compress together more efficiently. Adapted from the ZipPy research project by Thinkst Canary.

dictionary

Vocabulary Analysis

Checks for 130+ AI-favorite words in two tiers: 54 strong tells and 76+ moderate ones. Words like "delve," "tapestry," and "synergy" appear in AI output at rates dozens of times higher than in human writing.

pattern

Formulaic Patterns

Spots 30+ stock phrases that show up in AI output constantly. "In today's digital landscape," "When it comes to," "Let's dive in," and similar constructions.

straighten

Sentence Uniformity

Measures how much sentence lengths vary. AI text tends to produce sentences that hover around the same word count. Human writing swings between short and long.

show_chart

Burstiness

Human writing is bursty: short punchy sentences next to long winding ones. AI stays in a narrow band. Tracks consecutive similar-length pairs and paragraph-level uniformity.

shield

Hedging Language

Flags 20+ qualifier phrases like "It's important to note," "One might argue," and "perhaps most importantly" that AI uses to sound balanced.

more_horiz

Punctuation Patterns

Counts em dashes, semicolons, and colon-lists per 500 words. AI overuses these punctuation marks for a polished, editorial feel.

swap_horiz

Transition Overuse

Measures how many sentences start with "However," "Furthermore," "Moreover," and 20+ similar conjunctive adverbs that AI leans on heavily.

repeat

Repetitive Structure

Catches repeated paragraph openings, sentence-starting word patterns, and repeated endings that suggest templated generation rather than original writing.

Questions

Frequently Asked Questions

How accurate is this tool?
It combines nine heuristic categories including compression analysis adapted from the ZipPy research project. It catches common AI writing patterns reliably on unedited output of 200+ words. Use it as one signal among many, not as a final answer on whether a human or AI wrote something.
Does my text leave the page?
No. All analysis runs in your browser using JavaScript. No text goes to any server, API, or third party. Your content stays private.
Can AI text score low?
Yes. Heavily edited AI text, or text generated with specific style constraints, can score low. The tool catches common default patterns, not every possible configuration.
Can human text score high?
Sometimes. Academic writing, legal prose, and formal business writing use hedging language and transition words by convention. Some signals will fire. Context matters.
What languages are supported?
English only. The vocabulary lists, formulaic patterns, and hedging phrases are all English-specific.
Is there a word or usage limit?
No. Paste as much as you want, as often as you want. No daily caps, no account required.
How is this different from GPTZero or Grammarly's AI detector?
Those tools use server-side machine learning models, so your text goes to their servers for analysis. This tool runs entirely in your browser with transparent heuristic methods. You trade some ML accuracy for complete privacy and full visibility into what the detector checks for.