The Top AI Content Detectors You Already Use

Key Insights

• Using AI to generate writing and passing it off as your own is considered plagiarism.
• The effectiveness of services marketed specifically as AI content detectors varies significantly.
• Recent tests reveal that common AI chatbots can perform just as well, if not better, than these specialized tools.

Three years after generative AI exploded onto the scene, the battle against AI-generated plagiarism continues to evolve. This is an updated analysis based on extensive testing of AI content detectors that began in January 2023.

Initially, the best detector achieved only 66% accuracy. By February 2025, tests involving ten checkers saw three achieve perfect scores. A couple of months later, five detectors hit that mark. However, the landscape has shifted again. In the latest round of testing, the quality has declined, with only three detectors earning a perfect score. Some previously reliable tools have become less accurate and have added restrictions to their free versions.

The most significant discovery from this round of tests is a powerful new option that may make standalone detectors obsolete: the AI chatbot you already use.

The Testing Methodology

The core issue being addressed is plagiarism. According to Merriam-Webster, to plagiarize is to present another's work as one's own without credit. This definition applies when someone uses an AI tool like Notion AI or ChatGPT and claims the output as original.

To test the detectors, five text blocks were used: two written by a human and three generated by ChatGPT. Each block was fed into every detector, and the result was recorded as a pass or fail. The test samples are available in this document for anyone wishing to replicate the tests.

Performance of Dedicated AI Detectors

The tests were conducted across 11 different AI detectors, including BrandWell, Copyleaks, GPT-2 Output Detector, GPTZero, Grammarly, Originality.ai, QuillBot, Undetectable.ai, Writer.com, ZeroGPT, and the newcomer Pangram. Monica was dropped due to restrictive paywalls, and Pangram was added, immediately achieving a top score.

The results show a wide range of accuracy, with only a few tools providing consistently reliable results.

Despite multiple rounds of testing over time, there is no clear upward trend in reliability across the board. The inconsistency remains a major issue, as even human-written content can be flagged as AI-generated. Therefore, it is crucial to use these tools with caution.

The Surprising Power of AI Chatbots

Why bother with a separate content detector subscription when the chatbots we use daily might do the job? To find out, the same five text blocks were presented to several popular AI chatbots.

The results were striking. The chatbots demonstrated a much higher success rate than most of the dedicated "content detectors." The accuracy of the chatbots in these tests was consistently higher across the board.

Detailed Breakdown of AI Detector Tools

Here is a look at how each specialized tool performed:

• BrandWell AI Content Detection (40% Accuracy): No improvement since previous tests, incorrectly identifying two of three AI samples as human-written.
• Copyleaks (80% Accuracy): Despite claims of 99% accuracy, it incorrectly flagged human-written text as 100% AI-generated.
• GPT-2 Output Detector (60% Accuracy): An older tool that has not seen significant updates, its performance remains mediocre.
• GPTZero (80% Accuracy): While the platform has grown, its performance has fluctuated, getting different tests right and wrong in subsequent evaluations.
• Grammarly (40% Accuracy): The AI detection feature, now out of beta, showed no improvement and performed poorly.
• Pangram (100% Accuracy): A newcomer founded by ex-Google and Tesla engineers, Pangram delivered a perfect score in its first evaluation.
• Originality.ai (80% Accuracy): A paid service that previously scored perfectly, it declined in this round by misidentifying human writing as AI-generated.
• QuillBot (100% Accuracy): After overcoming previous inconsistency issues, QuillBot delivered a perfect 100% score for the second consecutive time.
• Undetectable.ai (20% Accuracy): This tool saw the most dramatic drop in performance, falling from a 100% score to just 20% by misidentifying nearly all samples.
• Writer.com AI Content Detector (40% Accuracy): This tool showed low accuracy, identifying all text samples as human-written, with no improvement over time.
• ZeroGPT (100% Accuracy): This service has matured from a sketchy ad-supported site to a professional tool, maintaining a perfect 100% accuracy score.

Detailed Breakdown of AI Chatbot Performance

Each chatbot was given the prompt, "Evaluate the following and tell me if it was written by a human or an AI," followed by the text sample.

• ChatGPT (Free Tier): This model was highly accurate, only getting one test wrong. Impressively, it not only identified a human-written text correctly but also identified its author, even when used in an incognito window.
• ChatGPT Plus, Copilot, and Gemini: All three of these premium chatbots delivered perfect scores, correctly identifying every human and AI-written text block.
• Grok: Despite its strong performance in other chatbot evaluations, Grok failed this test, incorrectly identifying three of the five samples.

Final Thoughts: Is a Dedicated Detector Necessary?

The evidence from this comprehensive testing suggests that for many users, a specialized AI content detector may not be necessary. Leading AI chatbots like ChatGPT Plus, Copilot, and Gemini have proven to be more reliable than many of the dedicated services on the market. While tools like Pangram, QuillBot, and ZeroGPT show promise, the convenience and accuracy of using a chatbot you likely already have access to present a compelling alternative.

What are your experiences with AI content detectors? Have you found them to be accurate, or have you seen human work mistakenly flagged as AI-generated? Share your thoughts in the comments below.