Top 6 Best Tools to Detect AI-Generated Content

Looking for the best AI detection tool but not sure which one to choose? We’ve tested and compared some of the most popular options to help you decide. We take a closer look at what makes each detector different and what you can expect from its results.

How We Chose the Best AI Detector

To create this list, we compared each AI detector based on several practical criteria that affect how useful it is in everyday use to detect if text is written by AI.

Criterion	What We Look For
Detection accuracy	How well the tool distinguishes AI-generated text from human-written content
False positives	How often human-written text may be incorrectly flagged as AI
Result detail	AI scores, classifications, sentence-level analysis, and highlighted passages
Free limits	How many words, characters, or scans you can check for free
Ease of use	How easy it is to paste text, upload files, run a check, and understand the result
Extra features	File uploads, browser extensions, integrations, and other writing tools
Price	The cost of paid plans and the limits or features included

How Do Programs Detect AI Writing?

AI detectors check for AI by analyzing patterns in a text and estimating whether they look more like human or AI-generated writing. Most modern detectors use machine learning models trained on examples of both types of content. Instead of looking for one definitive sign, they usually combine several linguistic and statistical signals to calculate an AI score. Here are some of the main characteristics they may analyze:

• Vocabulary and word patterns. Detectors examine vocabulary diversity, word frequency, and recurring phrases. AI-generated text may rely on a relatively consistent set of words and expressions throughout a passage.

• Sentence variation. Changes in sentence length and complexity create what is sometimes called burstiness. Human writing often has greater variation, while generated text may maintain a more regular rhythm.

• Repetition and structure. Similar sentence openings, repeated transitions, uniform paragraphs, and predictable ways of organizing ideas can create patterns that detectors associate with generated content.

• Syntax and punctuation. Sentence construction, grammatical patterns, parts of speech, clause structure, and punctuation provide additional signals that machine-learning classifiers can compare with human and AI training samples.

• Text watermarks. Some AI systems can intentionally introduce hidden statistical patterns by favoring particular word choices during generation. A compatible detector can identify this pattern even though it is not visible to the reader.

However, keep in mind that AI detectors use different models, training datasets, analyzed features, and classification thresholds. This means the same text can receive different AI scores depending on the detector you use. So treat an AI detection result as an estimate rather than definitive proof that a text was written by AI.

Top 6 Best AI Text Detector Tools

To compare the tools under similar conditions, we ran an AI check with the same types of samples: fully AI-generated text, AI-rewritten content, humanized AI text, AI-edited human writing, and fully human-written text. This helped us see how each detector handles different levels of AI involvement, as well as whether it incorrectly flags human writing as AI.

1. Clever AI Detector

Clever AI Detector is the best AI detection tool which combines strong detection with a simple workflow. In tests, it achieved the highest results for different types of AI-generated and edited content, with 96.7% overall AI detection accuracy. It correctly identified 100% of directly generated and AI-rewritten essays, 94.7% of AI-improved texts, and 92% of humanized AI content. It was the only detector to score above 90% across all four categories. It also recorded 0% false positives, correctly recognizing all human-written essays without flagging any of them as AI.

The detector is completely free and lets you check up to 10,000 words per scan with unlimited checks. You don't need to create an account to use it, but if you sign up, you also get access to your scan history. It has a clean, simple interface that makes it easy to paste your text, run a scan, and understand the results.

Once you paste your text, it provides an overall AI probability score and highlights individual sentences. It also shows which AI writing patterns it detects. This helps you better identify what needs improvement and quickly edit the problematic sections.

If the detector flags a large part of your draft, Clever AI Detector also offers a free humanizer AI content that can help make the entire text sound more natural. If only a short section needs work, you can use its rephrasing tool to paraphrase your text or sentence. The toolkit also includes a grammar checker, which can help you catch grammar, spelling, and punctuation issues after editing.

Key features:

• Up to 10,000 words per check

• Unlimited free checks

• No sign-up required

• Overall AI probability score

• Sentence-level highlighting and AI ratings

• Strong AI detection performance in tests

• Low risk of false positives

• Scan History available with an account

• Free AI Humanizer and Paraphraser

Price: Free

2. Copyleaks

Copyleaks is a more advanced AI detector that showed strong and consistent results across different types of AI content in tests. It showed 95% overall AI detection accuracy. AI checker correctly detected 100% of directly generated and AI-rewritten content, 93.3% of humanized AI text, and 86.7% of AI-improved essays. Copyleaks produced 0% false positives.

You can run a basic scan without creating an account, but it only shows the overall AI score. To access the detailed report, you need to sign up. After registration, you receive 5 free scan credits, with up to 1,000 words per credit.

The detailed report goes beyond a single percentage. It color-codes the text to distinguish passages that appear AI-generated from those that look human-written. AI Phrases identifies phrases that appear more frequently in AI-written content, while AI Source Match can find AI-generated text that matches content used elsewhere. The interface is easy to navigate, so you can quickly understand how to paste their text and run a scan. However, the results lack detailed explanations of why specific passages were flagged or how to improve them.

Copyleaks also includes a plagiarism checker, while its Chrome extension and Google Docs integration let you check content directly while you write or edit.

Key features:

• Up to 1,000 words per scan

• AI score and text highlighting

• AI phrase detection

• AI source matching

• Built-in plagiarism checker

• Chrome extension

• Google Docs integration

• Strong and consistent detection results in tests

Price:

• Personal – $16.99/month, 25,000 words or 100 images, AI and plagiarism detection, 30+ AI detection languages, 100+ plagiarism detection languages, Shared Data Hub, batch uploads, browser extension, Google Docs add-on, and MCP access.

• Pro – $99.99/month, everything in Personal, plus 250,000 words or 1,000 images, 25 user seats, advanced detection filters, website scanning, cross-language detection, and analytics dashboard.

3. Originality.ai

Originality.ai is a more feature-rich detector that got 86.8% overall AI detection accuracy. It correctly identified 100% of directly generated and AI-rewritten essays and performed particularly well with AI-improved content, reaching 96%. However, its detection rate dropped to 51.3% for humanized AI text. Despite this limitation, Originality.ai recorded 0% false positives.

The free detector lets you check up to 2,000 words per scan with 3 free scans per day. The interface is clean and intuitive, with straightforward navigation. It provides an AI confidence score and highlights the parts of the text that contribute to the result. You can also adjust the AI allowance, which lets you choose how much AI-generated content you consider acceptable before the text is flagged.

Originality.ai also includes a plagiarism checker, plus additional tools such as a grammar checker, readability checker, fact checker, and content quality checker. This makes it useful if you want to evaluate more than just AI probability in one place.

Key features:

• Up to 2,000 words per free scan

• 3 free AI scans per day

• AI confidence score

• Text highlighting

• Adjustable AI allowance

• Built-in plagiarism checker

• Strong performance on AI-generated and AI-edited content

Price:

• Pro – $14.95/month, 200,000 words/month, 30-day scan history, Deep Scan, bulk scanning, file uploads, PDF reports, team management, and full browser extension access.

• Enterprise – $179/month, everything in Pro, plus 1.5 million words/month, 1-year scan history, API access, additional team seats ($24.95/month each), and priority support.

4. Winston AI

Winston AI showed strong results with directly generated and AI-rewritten content and achieved 82.7% overall AI detection rate. It correctly identified 100% of directly generated and AI-rewritten essays, along with 86% of AI-improved content. However, humanized AI text was more challenging, with only 44.7% detected. Winston AI also maintained a 0% false positives rate.

To use Winston AI you need to create an account before you can run a scan, but after registration, you get 2,000 free credits to test the platform. It has a clear, user-friendly interface that is easy to navigate, even for first-time users.

The detector provides an overall score and highlights individual sentences based on four categories: Likely AI, Uncertain, Mostly Human, and Human. This makes it easy to see which specific parts of the text may need a closer look. Winston AI also saves your previous checks in Scan History, so you can return to earlier results.

Besides AI detection, the platform includes a plagiarism checker and supports integrations such as Chrome, Firefox, Microsoft Edge, Google Classroom, WordPress, Zapier, and more.

Key features:

• 2,000 free credits after registration

• Overall Human Score

• Sentence-level AI highlighting

• Likely AI, Uncertain, Mostly Human, and Human classifications

• Scan History

• Built-in plagiarism checker

• Chrome, Firefox, Edge, Google Classroom, WordPress, and other integrations

Price:

• Essential – $18/month, 100,000 credits/month, AI text and image detection, writing feedback, document and handwriting scanning (OCR), PDF reports, and email/chat support.

• Advanced – $29/month, Everything in Essential, plus 200,000 credits/month, advanced plagiarism detection, HUMN-1+ certification, and up to 5 team members.

• Elite – $49/month, Everything in Advanced, plus 500,000 credits/month, unlimited team members, and additional credit purchases.

5. Pangram

Pangram showed its strongest results with fully AI-generated content. In tests it had 67.5% overall AI detection accuracy. It correctly identified 100% of directly generated essays and 88% of AI-rewritten content. It also detected 64% of humanized AI texts, but its performance dropped significantly for AI-improved essays, with only 18% correctly flagged. Pangram nevertheless recorded 0% false positives.

You need to create an account to run free checks. The free plan gives you 20 credits, with 1 credit used per 100 words. The interface is clean, intuitive, and easy to navigate, making it simple to submit text and review detection results. You can paste the text directly, upload a file, or enter a URL to scan content from a webpage. After each scan, Pangram provides an overall AI result and uses color-coded highlights to classify text as AI-generated, AI-assisted, or human-written. It also offers a more detailed view of individual text segments.

Pangram also includes a plagiarism checker, a Chrome extension, and integrations with services such as Canvas and Google Classroom. It also offers AI image detection and an API for larger-scale use.

Key features:

• Strong detection of fully AI-generated text

• Overall AI detection result

• AI text and segment highlighting

• 20 free credits after registration

• 1 credit per 100 words

• Built-in plagiarism checker

• Chrome extension

• Canvas and Google Classroom integrations

• AI image detector and API

Price:

• Individual – $20/month, 300,000 words/month, 100 AI image scans, similarity detection, social media scanning, file uploads with OCR, Pangram MCP, Google Docs and Gmail integrations, and a 7-day free trial.

• Professional – $65/month, everything in Individual, plus 1.5 million words/month, 500 AI image scans, and $200 in monthly API credits.

• Team – $40/month (2 seats), everything in Individual, plus an admin and member dashboard, unified billing, and additional seats at $20/month each. Includes a 7-day free trial.

6. QuillBot

QuillBot AI Detector is a convenient option if you want to run a quick AI check without creating an account. Test results showed 64.2% overall AI detection accuracy. It correctly detected 100% of directly generated essays and 96.7% of AI-rewritten content. However, its performance dropped to 38% for AI-improved essays and just 22% for humanized AI text. It also struggled with shorter samples, detecting only 12.5% of AI-involved texts under 200 words. Also, QuillBot produced 0% false positives.

The free version lets you scan up to 1,200 words per check. The interface is clean, straightforward, and easy to navigate, so even first-time users can quickly understand how to run a check and interpret the results.

The detector gives you an overall AI percentage and breaks the result down into categories such as AI-generated, Human-written & AI-refined, and Human-written. It also highlights the text and points out the sentences that show the strongest AI signals, so you can quickly see which parts may need attention.

QuillBot also has a broader set of writing tools. You can send problematic text directly to its Paraphraser, use the AI Humanizer for larger edits, or run a plagiarism check. It also offers a Chrome extension and keeps previous checks in History when you use an account.

Key features:

• AI checks without an account

• Overall AI percentage

• AI-generated, AI-refined, and human-written classifications

• Sentence-level AI analysis and highlighting

• Paraphraser and AI Humanizer

• Plagiarism checker

• Chrome extension

• Scan History for signed-in users

Price:

• Premium – $19.95/month, full access to AI detection, unlimited paraphrasing modes, AI Humanizer, advanced grammar suggestions, custom summaries, and plagiarism checking.

AI Detectors Quick Comparison Table

The table below compares the six AI detectors based on their performance in our tests, false positive rates, free usage limits, key features, and pricing.

AI Detector	Overall AI Detection Rate	False Positives	Free Limits	Key Features	Paid Plans From
Clever AI Detector	96.7%	0%	Unlimited scans; 10,000 words/check	Sentence-level analysis, AI pattern explanations, Humanizer, Paraphraser	Free
Copyleaks	95%	0%	5 credits; 1,000 words/credit	AI phrase detection, source matching, plagiarism checker	$16.99/month
Originality.ai	86.8%	0%	3 scans/day; 2,000 words/scan	AI allowance settings, plagiarism and fact checking	$14.95/month
Winston AI	82.7%	0%	2,000 credits after sign-up	Sentence classifications, plagiarism checker, OCR	$18/month
Pangram	67.5%	0%	20 credits; 100 words/credit	Segment highlighting, AI image detection, integrations	$20/month
QuillBot	64.2%	0%	1,200 words/check	Sentence highlighting, Paraphraser, AI Humanizer	€19.95/month

Conclusion

If you’re looking for the best AI detector, Clever AI Detector is our top recommendation. It achieved the highest overall detection accuracy in our tests at 96.7%, performed particularly well with humanized AI text (92%), and correctly identified all human-written essays without false positives. Unlike many competitors, it's completely free, requires no registration, and allows unlimited scans of up to 10,000 words each. Its clear sentence-level analysis, AI pattern explanations, and additional writing tools make it a practical choice for anyone who needs reliable AI detection without paying for a subscription. Overall, it is a strong option for anyone looking for the best free AI content detector without sacrificing useful features.

Frequently Asked Questions

What is the best free AI detector?

Based on our tests, Clever AI Detector is the best free AI detector. It performed well across different types of AI content, showed a low risk of false positives, and provides useful text analysis without a paywall.

Can AI detectors tell for sure if a text was written by AI?

No. AI detectors analyze linguistic and statistical patterns and calculate a probability or score. Their results should be treated as an estimate rather than definitive proof of authorship.

What should I look for in an AI detector?

Look at detection accuracy, false positives, the level of detail in the results, ease of use, free limits, and additional features. Sentence-level analysis and highlighting can be especially useful when you want to understand which parts of a text triggered the result.

Do AI detectors work on short texts?

They can, but short texts usually provide fewer patterns for a detector to analyze. As a result, scores for very short passages may be less reliable than results for longer content.