AI Content Detector

Check if text was written by AI with a sentence-by-sentence heatmap.

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What is an AI Detector?

An AI detector is a free tool that tells you if a piece of writing was made by a human or an AI like ChatGPT. You paste in text, and it reads the writing patterns and gives you a score plus an easy to read report.

It helps teachers check student work, writers polish content before publishing, and SEO teams keep their sites safe from Google penalties. Our detector goes further than most with a sentence-by-sentence heatmap and a guess at which AI model likely wrote the text.

How It Works

Paste or upload your text

Paste any text into the box. You can also upload a PDF, DOCX, or TXT file, or drop in a web page URL.

AI reads your writing

Our tool checks word patterns, sentence rhythm, and meaning. It runs two checks at the same time to catch AI content other tools miss.

Get a clear report

See an overall verdict, a confidence score, a color-coded heatmap for each sentence, and the most likely AI model that wrote it.

Features

Sentence-by-sentence heatmap

Every sentence gets a color. Green, yellow, or red. Click any sentence to see why it scored that way.

Three-tier classification

Human Written, AI Assisted, or AI Generated. A useful answer, not a basic yes or no.

Source model prediction

Guesses which family of AI tool wrote the text based on common writing-pattern fingerprints.

Detailed metrics

See perplexity, burstiness, vocabulary variety, and sentence uniformity for every scan.

Many input methods

Paste text, upload a PDF or DOCX, or submit a URL. We pull the text out for you.

Two-layer engine

Statistical checks run alongside AI analysis. Two views of the same text, fewer false positives.

Why Use an AI Content Detector?

Trust your content

Ship writing you know reads as human before a teacher, client, or editor ever sees it.

Fix what the detector flags

See the exact sentences that look AI generated and rewrite just those parts.

Results in seconds

A full scan of a 5,000 word essay finishes in under 3 seconds.

Your text stays private

We do not store your text or use it to train any model. Every scan runs on an encrypted connection.

Who Is This For?

Teachers and professors

Check student submissions before grading. The heatmap shows which sections need a closer look.

Students

Self-check essays before you turn them in. Make sure your writing sounds like you.

Content writers

Keep published articles under the AI thresholds clients and ad networks now require.

SEO pros

Audit site copy at scale. Google now ranks detectable AI content lower in competitive niches.

Recruiters and HR

Screen cover letters and applications to spot candidates who put in real effort.

Legal and compliance

Flag AI generated filings, contracts, or testimony where human authorship is a rule.

Real Use Cases

1You just wrote a blog post and want to make sure it reads as human before you publish.
2You teach a class and want to spot-check suspicious student work before grading.
3You got a freelance article back from a writer and want to know if AI helped write it.
4You are a student running a final essay through a check before the deadline.
5You run a content site and need every post to pass Google's helpful content update.
6You review job applications and want to filter real cover letters from ChatGPT ones.

AI Detector vs Plagiarism Checker

These two tools answer different questions. An AI detector asks “was this written by AI?”. A plagiarism checker asks “was this copied from somewhere else?”. Smart writers use both.

Feature	AI Detector	Plagiarism Checker
Main purpose	Checks if text was written by AI	Checks if text was copied from other sources
How it works	Reads language patterns and predictability	Matches text against a database of published content
What it catches	AI written text even if fully original	Copied or paraphrased text from known sources
Common false flags	Very formulaic human writing may flag	Common phrases and quotes may flag
Use them together	Yes. Different checks that complement each other	Yes. Neither tool replaces the other

The Science in Plain English

Predictability (also called perplexity)

AI writes by picking the most likely next word over and over. The result is text that feels a bit too predictable, like it never surprises you. Humans make odd word choices, drop in idioms, and switch tone mid-sentence. Our detector measures how predictable each part of the text is. Too predictable is a red flag.

Sentence rhythm (also called burstiness)

Humans mix short punchy sentences with longer ones that carry more detail. AI tends to write sentences that are all about the same length. We measure how much the sentence length changes across your text. A flat rhythm often means AI. A lively, uneven rhythm usually means human.

Word variety and patterns

AI models reuse the same favorite phrases and transitions. They also avoid rare or specialized words unless you specifically ask for them. We check how varied your word choices are and look for repeating patterns. When we combine these checks with the other signals, we catch AI writing that a single metric would miss.

Frequently Asked Questions

Is this AI detector free?

Yes. You can run up to 25 scans per day for free with no signup and no credit card, and up to 50,000 characters per scan. Upgrade to Pro for unlimited scans, faster speed, and file history.

How accurate is the AI detector?

Our AI detector uses two layers of analysis at the same time. First it measures language patterns like word choice, sentence variety, and predictability. Then an AI model reads the text for deeper meaning. This double check gives strong accuracy for English text, but no detector is perfect. We always show a confidence score so you can judge the result yourself.

Can it detect ChatGPT and Gemini?

Yes. The tool spots content from ChatGPT, Gemini, and other popular AI writing tools. It also estimates which family of model likely wrote the text based on writing patterns common to each one.

What does the sentence-by-sentence heatmap show?

Every sentence gets its own color. Green means likely human. Yellow means mixed or unclear. Red means likely AI. Click any sentence to see why it was scored that way, so you know exactly which parts look AI generated.

What is three-tier classification?

Most basic tools only say AI or Human. We use three labels: Human Written, AI Assisted, and AI Generated. Real writing today is a mix, so this gives you a more useful answer than a simple yes or no.

Is this a free Turnitin alternative?

Yes. You get AI detection features similar to Turnitin without needing a university subscription. 25 free scans per day, sentence-level analysis, model prediction, and detailed metrics. Pay nothing unless you want more daily scans.

What should I do if my own writing was flagged as AI?

Add personal voice, opinions, and stories you actually lived through. Vary your sentence length so some are short and some are longer. Skip formal phrases that sound like templates. Include real data or examples. Remember, any AI detector is a helper, not the final word on your writing.

Does the AI detector work for non-English text?

The detector works best on English. You can try it with other languages but accuracy drops. We are working on full support for more languages and will ship it soon.

What file formats can I upload?

You can paste text directly, upload a PDF, DOCX, or TXT file, or paste a web page URL. We pull the main text out of the file or page for you. Minimum 100 characters. Maximum 50,000 characters per scan.

Is my text private when I run a scan?

Yes. We do not store your text after the scan. Stats are computed on our server, and the AI model reads your text over an encrypted connection. We never use your text to train models or share it with anyone.

Built by Molixa

Molixa builds 60 plus free AI tools for students, writers, and busy professionals. No signup to try any of them. No credit card for the free tier. Built to feel fast and stay out of your way.

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Built and reviewed bySaqib Zahoor, WeboTech Studio

Last updated: May 14, 2026

The AI Content Detector page is built, reviewed, and maintained by the Molixa team. We use the tool we ship and update the docs when the behavior changes.

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