Quillbot AI Content Detection Review: How Accurate is it?

AI writing tools are only becoming more popular and so figuring out how to detect AI writing has become a growing concern. As the marketplace for AI detectors is becoming more crowded, it’s important to be able to tell the difference between the various options. 

In this QuillBot AI content detection review, we look at how QuillBot’s AI detector works, how accurate QuillBot’s AI detector is, and what its pricing looks like. But in a nutshell, as we will explore further below, Quillbot is a writing assistant that includes an AI detector, but it is less effective than dedicated tools such as GPTZero.

What is Quillbot’s AI Detection?

It’s crucial to note that Quillbot did not initially start as an AI detector. In fact, Quillbot first launched in 2017 as a paraphrasing tool designed to help students improve their English writing, and has since evolved to become a broader writing assistant. In 2021, Quillbot was acquired by Learneo, Inc. (formerly known as CourseHero), which also owns the popular study aid services CliffNotes and citation generator Scribbr.

It was only in July 2024 that Quillbot introduced its AI detection tool, aimed at helping users identify whether a piece of content was generated by AI or written by a human. Meanwhile, GPTZero, the first AI detector, was launched in January 2023, followed by other AI detection features from companies like TurnItIn. 

These detectors all serve educators and students where it is important to establish academic integrity when it comes to written work - academic integrity that comes under scrutiny when tools like Quillbot’s paraphraser (its flagship offering) are part of the mix. It’s a tool that allows users to rework text in different modes according to whether they want something in a certain tone.

How Does Quillbot AI Detection Work?

As a user, this video walks you through exactly how to check AI-generated content using the QuillBot AI detection tool and understand your results clearly.

When you look behind the tool, according to QuillBot, its AI Detector uses a “custom model architecture” and is also trained to identify “paraphrased text, AI rewrites, and mixed human-AI writing”. 

QuillBot says its detector works at a more granular level than simple document-wide scanning, and analyzes text “at the sentence level rather than document-wide”, which allows it to flag specific AI-generated sections within mixed content. 

QuillBot evaluates writing using signals such as word patterns, sentence variety, and probability to assess authorship, also claiming to categorize AI content across 10 specific patterns, including “overly formal tone, technical jargon, predictable structure, and generic language.” These are the tell-tale signs of AI-generated writing that we’ve written about in the past, revolving around repetitive phrasing and generic sentence structures, all with a robotic or vanilla tone. 

QuillBot says it uses probabilistic scoring, with confidence categories such as “low,” “moderate,” and “high.” It also supports “mixed” classifications, which means it can distinguish between fully human writing, fully AI-generated writing, and documents that sit somewhere in between.

How Accurate Is QuillBot's AI Detector?

To determine how reliable AI detection tools are, we run our own benchmarking tests with a variety of texts, including human-written articles, AI-generated content, and hybrid pieces that blend both styles.

You can find all our benchmarks here.

Independent tests done by journalists show Quillbot at 80% Accuracy. 

Independent findings show that Quillbot's AI detector is reasonably accurate, but it may be overturned to be more likely to predict AI when the writing was actually written by humans, meaning it has a high chance for false positives. As with all AI detection tools, the accuracy of results depends often on the type of text chosen and its length.

Other Key Features of Quillbot

• Quillbot Paraphraser: Quillbot's Paraphrasing tool is one of its most popular features, designed to reword text in a variety of ways while preserving the original meaning. Users can choose from several writing modes such as Standard, Fluency, Formal, and Creative.
• Summarizer: The Summarizer tool on Quillbot helps condense long articles, essays, or research papers into short summaries that attempt to cover the key points and important information. This tool is used by students, researchers, or anyone who needs to quickly digest large amounts of text. The summarizer offers both a Key Sentence and Paragraph summary mode, giving users control over the level of detail they want to retain in their summary.
• Plagiarism Checker: Quillbot allows users to scan their content for potential plagiarism by comparing it against online sources, including websites, academic papers, and books. The tool highlights the sections of the text that may be plagiarized and provides links to the sources where the matches were found.

Pricing: How Much is Quillbot?

Quillbot offers both a free version and a premium subscription plan, making it accessible to a wide range of users. Here’s a breakdown of the pricing structure:

• Free Plan: The free version of Quillbot includes limited features, such as:
  • Paraphrase up to 125 words
  • Fix basic grammar errors
  • Humanize text in Basic mode
  • Generate basic summaries
  • Access AI Detector (1,200 words)
• Premium Plan: Priced at $8.33 per month if you pay yearly, the premium subscription offers everything above as well as:
  • Unlimited text paraphrasing
  • Premium grammar recommendations
  • Humanize text in Advanced mode
  • Custom summaries
  • AI Detector (unlimited words)
• Team Plan: Starting around $7.50/user/month (for 2-10 users), billed annually, with everything in the Premium plan plus: 
  • Team style guide & dictionary
  • Admin panel and usage report
  • Writer management dashboard
  • Data controls
  • Centralized billing

What this shows is that Quillbot is presenting itself as a broader writing productivity platform, with AI detection as only one small piece of what it does. The pricing is built around paraphrasing, grammar, summarising, “humanising” text, and team workflows, and it suggests that detection is not the sole centre of gravity in the way it is for tools built primarily around authorship analysis.

Alternatives to Quillbot AI Detector

When it comes to AI detection, it's important to test the accuracy of tools to avoid false positives. Several other AI detection tools on the market offer similar functionality to Quillbot, including:

• GPTZero: Launched in January 2023, GPTZero was designed specifically to detect AI-generated text. It has gained popularity for its impressive accuracy rate of 99.5%. GPTZero’s algorithms are continuously updated to handle the latest AI models, making it one of the most reliable tools for AI detection.
• Turnitin: Known primarily for plagiarism detection, Turnitin also offers AI detection capabilities. It’s widely used in educational institutions and has a robust database of academic papers for comparison.
• Originality: Another plagiarism detection tool that includes AI detection. It’s ideal for educators and professionals who need to check large volumes of content for both plagiarism and AI generation.
• Copyleaks: Copyleaks is an AI detection tool designed for various use cases, from academic writing to professional content creation. Its AI detection is highly regarded in the industry.

GPTZero vs. Quillbot: What’s the Difference?

As we’ve already seen, the biggest difference between GPTZero and QuillBot comes down to what each product is fundamentally built to do, and who it is built for.

GPTZero is an AI detection and authorship analysis platform, and the core mission is to help educators, institutions, and organizations gauge whether writing is likely to be human, AI-generated, or somewhere in between. QuillBot, on the other hand, started as a paraphrasing tool and broader writing assistant with helping people rewrite, rephrase, summarise, and polish text, with plagiarism and AI detection added on top.

GPTZero is focused on verification: helping users review writing carefully, interpret AI signals responsibly, and make better-informed decisions in academic and professional settings. QuillBot is focused more on text transformation, for writers who want to improve flow, change wording, simplify sentences, or make a piece sound smoother and more natural.

QuillBot’s AI detector makes sense within that broader bundle, as it gives users a way to check text inside the same platform where they may also be paraphrasing, editing, or summarising it. Meanwhile, GPTZero is built around detection first, with related tools such as plagiarism detection and source citation designed to support that core authorship workflow.

Depth matters, too: GPTZero is built for people who need more than a surface-level score, such as sentence-level analysis, more detailed reporting, and features designed for educational and institutional review. GPTZero is also the most regularly updated AI detector available, as shown by the 15 different model releases in 2025, and there is a high level transparency around benchmarking.  

GPTZero also offers API access to its detection model, making it useful for enterprises, publishers, platforms, and software companies that need deeper AI analysis built into their own workflows. So while both tools might include AI detection, they come from very different philosophies: QuillBot is a writing assistant with detection built in, while GPTZero is a dedicated detection platform built for authorship transparency.

Who Should Use GPTZero or Quillbot?

QuillBot is best suited to students or those whose main goal is to paraphrase, tidy up grammar, generate summaries, check for plagiarism, and run a quick AI scan all in the same place. If that’s what you’re looking for then QuillBot makes sense as a convenience product.

GPTZero is better suited to educators, content teams, and institutions that need AI detection to be more than a side feature, and it’s also helpful for students who want to do a granular ‘pre-submission’ check on their work, to make sure it doesn’t get flagged for AI. 

GPTZero’s priority is authorship analysis: distinguishing between human and AI-generated writing, reviewing mixed text more carefully, and applying those signals in academic, editorial, or professional settings. In a nutshell, QuillBot is built more for writing assistance, while GPTZero is built more for verification and review.

That gap shows up in how paraphrased AI text behaves under detection. As one review from Netus AI put it, “The main reason QuillBot struggles to bypass AI detectors is that it primarily focuses on rewording rather than restructuring or deeply altering the content. GPTZero and similar tools analyze more than just surface-level language changes; they assess underlying patterns, sentence structures, and the overall ‘fingerprint’ of AI-generated content. This means that even if QuillBot changes some words and phrases, the text may still retain characteristics typical of AI-written content, making it detectable by GPTZero.”

It’s a helpful distinction as it gets at the heart of what separates a rewriting tool from a detection platform: one is trying to help users reshape language on the surface and the other is looking beneath that surface at authorship patterns that are harder to paraphrase away.

FAQ

Is QuillBot AI Detector free?Yes, QuillBot offers access to its AI Detector on the free plan, but with limits. The free version includes AI detection for up to 1,200 words, while paid plans expand that access, including unlimited words on Premium.

How accurate is QuillBot’s AI Detector?Independent tests done by journalists put QuillBot at around 80% accuracy, although as with all AI detection tools, results depend on the type of text chosen and its length. QuillBot may be more likely to predict AI when writing was actually written by humans, creating a higher risk of false positives.

Can QuillBot detect ChatGPT writing?According to QuillBot, yes: its AI Detector is built on a custom model architecture designed to detect text generated by ChatGPT, Gemini, Claude, and other AI platforms. It also says it can identify paraphrased text, AI rewrites, and mixed human-AI writing, not just fully AI-generated content.

What’s the difference between QuillBot and GPTZero?The biggest difference is that QuillBot is a writing assistant with detection built in, while GPTZero is a dedicated detection platform built for authorship transparency. QuillBot is focused more on paraphrasing, rewriting, and polishing text, whereas GPTZero is focused on verification, review, and deeper authorship analysis for educators and institutions.