Quillbot AI Detector Review 2026: Is It Accurate?

Qullbot is well-known for helping you rewrite your text. But can its AI detector differentiate accurately between human and AI writing?

It’s a convenient and fast AI checker, but its performance varies depending on the content type and how it was produced.

Detectors analyze patterns in writing to assess the probability of a piece being written by a human or machine-generated. Thus, detector results should be part of analysis and not the definitive proof of authorship.

To understand its capabilities, Quillbot was tested across six different writing samples covering human-written, AI-generated, AI-edited, and AI-assisted text.

Quillbot AI Detector Review: Quick Verdict

• Best for: Quick AI-writing checks with straightforward results.
• Not ideal for: High-stakes environments like academic circles, legal settings, and publishing houses.
• Overall score: 7/10

What Is the Quillbot AI Detector?

Quillbot is a browser-based AI detector designed to check samples for AI scores. It also offers a paraphraser, plagiarism checker, grammar checker, summarizer, humanizer, and citation generator.

It aims to serve multiple groups, including:

• Students
• Teachers and educators
• Writers
• Researchers
• Businesses
• Editors and content teams

Quillbot offers sentence-level feedback (paid plan), which helps you inspect different portions of your document. To check your content, make sure you add a minimum of 80 words.

How We Tested Quillbot’s AI Detector

Each sample was between 500 and 1,000 words, giving Quillbot ample material to analyze text.

1. Human-written text

The human text was correctly identified by Quillbot, assigning it a 0% AI score.

2. ChatGPT-generated text

Even the ChatGPT text was correctly identified by Quillbot with a 100% AI score.

3. Claude-generated text

Claude’s writing style did manage to mislead Quillbot with just a 37% AI score, signalling false negatives.

4. Gemini-generated text

A 92% AI score for Gemini content is acceptable though not perfect.

5. AI text heavily edited by a human

The editing brought the AI score to 40%.

6. Human writing polished with AI

The human sample was run through a paraphraser. It led to a slight jump in the AI score, which is fine.

Winston AI’s Detection Results

Let’s see how Winston AI performed across the six samples.

1. Human-written text

All the sentences—individually—received a 100% human score.

2. ChatGPT-generated text

The ChatGPT sample was correctly identified by Winston AI, with each sentence receiving a 0% human score.

3. Claude-generated text

Claude’s AI patterns were correctly identified by Winston AI, and it received a 1% human score.

4. Gemini-generated text

Even Gemini couldn’t pass the advanced detection mechanisms followed by Winston AI.

5. AI text heavily edited by a human

The heavily edited human text also received a 0% human score.

6. Human writing polished with AI

Paraphrasing human text slightly reduced the human score, which is justified as Winston AI highlighted what added to the AI score.

How Does Quillbot Detect AI?

Here’s how Quillbot detects AI:

• It predicts how likely the next word or phrase is within a passage.
• Quillbot analyzed if certain linguistic patterns occur unusually often.
• Humans may write in long and short sentences, and AI writing has similar sentence lengths. Quillbot checks if the text has multiple sentences with similar word counts.

Quillbot tries to differentiate between human, AI-generated, and human-written but AI-refined writing. It struggles to detect hybrid writing accurately; thus, you shouldn’t rely on AI scores completely.

Quillbot AI Detector Features

Quillbot’s main features include:

• Browser-based checking
• Sentence-level analysis
• AI-writing classification
• Support for longer pieces of text
• Straightforward results
• Accessibility for students, writers, and educators

The interface is one of its strongest selling points. Even if you have never used a detector before, you can easily use it.

Quillbot AI Detector vs Winston AI

The two tools serve common detector expectations, but their feature sets and presentation differ.

Quillbot vs. Winston AI Test Scores

Quillbot AI Detector: Pros and Cons

Let’s look at the pros and cons of using Quillbot.

Pros

• Quillbot can easily be used by first-time users.
• You get the results in seconds, and it works directly through the browser.
• Paid plans offer sentence-level highlights, helping you understand the reasons for high AI scores.

Cons

• Content produced by Claude was given a very low AI score (37%).
• Heavily edited AI text (40%) also received largely incorrect AI scores, signaling false negatives.

Is Quillbot AI Detector Free?

With Quillbot’s free plan, you can check up to 1200 words/search and do 10 scans in a day. There’s no such limit in the paid plan. You can buy the premium plan starting from $19.95/month if the free plan doesn’t suffice your needs.

Is Quillbot AI Detector Accurate? Final Verdict

Quillbot correctly identified 4/6 samples. It performed best on human-written and ChatGPT-generated samples. Quillbot didn’t perform well on the Claude sample and the AI sample edited by a human. Quillbot can be used to rule out 100% AI content but is not a reliable option for hybrid content.

This reiterates the fact that AI detection should never be considered the absolute truth. Quillbot also advises that detector results should never be the sole basis for decisions that could affect someone’s academic standing or career. A sensible approach is to consider drafting history, sources, and other available evidence alongside detector results.

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