Claire FountainChatGPT has revolutionized the tech world, making high-quality AI content generation free and available to the masses.
Google does not classify AI content as spam, whatever you have read elsewhere. It has said since February 2023 that it rewards good content however it is made. What it does demote is thin work published at volume, which is where unedited drafts land.
A detector is still worth running. Not to dodge a penalty, but because a low score usually means the writing is predictable and needs work.
I had ChatGPT itself write me a paragraph and used that to test dozens of free ChatGPT output detectors to get you this list of the best ones.
Best All-In-One: AI Detector + Rewriter
- Detects AI by cross-checking 8 other detectors
- Easy-to-use rephrasing tool
- Readability features are great for different tones
Best Plagiarism Checker + AI Paraphrasing Tool
- Can rewrite long-form content, not just paragraphs at a time
- Built-in plagiarism checker
- Offers other free tools like AI image detector
We offer this website completely free to our visitors. To help pay the bills, we’ll often (but not always) set up affiliate relationships with the top providers after selecting our favorites. However, we do our best not to let this impact our choices. There are plenty of high-paying companies we’ve turned down because we didn’t like their product.
An added benefit of our relationships is that we always try to negotiate exclusive discounts for our visitors.
Key Takeaways
- Free ChatGPT output detectors estimate how machine-made your writing reads. They do not measure Google risk and they do not prove authorship
- Sapling is our pick of the free ones. The Content at Scale detector we used to recommend was retired when the company became BrandWell
- Run drafts through a detector before publishing, then edit what it flags. The point is a better article, not a passing score
Our Favorite ChatGPT Output Detectors
Here are our 5 favorite free ChatGPT output detectors.
- Sapling AI (4.5/5) – Runner-up for best free detector
- Writer (4/5) – Best for writers
- Content at Scale – retired. The company is now BrandWell and no longer offers a detector
- Undetectable AI (4/5) – Best multi-source ChatGPT checker
- Kazan SEO (3/5) – Best additional tools and features
1. SaplingAI
Runner-up for best free detector – 4.5/5 Rating
With the ability to check for every kind of AI writing, Sapling.ai’s AI content detector is a thorough, easy-to-use tool available entirely for free.
It’s recommended to include more than 50 words of text, as the more it is able to read, the more it is able to detect.
Once you type in at least 50 words or “tokens,” this AI detector will give users a “Real probability” and “Fake probability” score that users can compare to each other and see whether the content seems more “human” or more “machine.”
Here are our test results:
2. Writer
Best for writers – 4.0/5 Rating
With a straightforward name, Writer is a leader in… well, written content creation.
It also has an easy-to-use AI content detector to make it easy for users to check their AI-generated content before sending it out into the world. This detector has ChatGPT and GPT-3 detection abilities as well as GPT-2.
Similarly to Content at Scale’s AI detector, Writer’s shows a detection score in percentage.
If you need help, they have a dedicated customer support team as well.
3. Content at Scale
Best free AI detector & part of our favorite AI writing tool – 4.0/5 Rating
Update, September 2026: this detector no longer exists. Content at Scale rebranded to BrandWell in 2024 and has since moved into intent data and go-to-market tooling. The detector was spun out into a Chrome extension called Moxby by the same founder. Sapling above is our free pick now. If you can pay, Originality.AI is the most dependable, and we compare the rest in our detector roundup.
What follows describes the detector as we tested it.
We love this detector because it has the ability to detect when content comes from ChatGPT, GPT-3, or any other AI model within moments.
You can start by generating your content using Content at Scale’s AI writing service, and then check for its human-like quality using the built-in detector before posting.
It gave you a score out of 100 on how human the content read, then broke that down into the elements behind it. You’ll be able to see how your content scored in predictability, probability, and pattern.
Another new feature we’re excited about is the sentence-by-sentence breakdown. The detector will highlight each sentence of content in a color that corresponds to its detectability, so you can fix the sentences that appear to be AI-written and not worry about sentences that already work.
An added bonus: most of the Content at Scale content ran through it earns a high “Human Content Score,” so you have to do less work on editing it.
Check out our full review of Content at Scale
Here are the results from our AI test:
4. Undetectable.AI
Best multi-source ChatGPT checker – 4.0/5 Rating
Undetectable.ai has a free AI detector that can detect content created by ChatGPT.
It’s unique in that it aggregates results from 8 different popular ChatGPT AI detectors, so you’ll get AI detection likelihood scores from GPTZero, OpenAI, Writer, Crossplag, Copyleaks, Sapling, Content at Scale, and ZeroGPT, all in one place.
You can enter up to 10,000 characters at a time, which makes it great for shorter paragraphs written by ChatGPT.
We found it to be pretty good at detecting ChatGPT content because of this, but it does struggle in misidentifying human-written content as AI at times. If you’re using it to test ChatGPT, however, this shouldn’t be a problem.
Unfortunately, its reference points seem to be having and off day. Here are the results from our AI test:
5. Kazan SEO
Best additional tools and features – 3.0/5 Rating
For an all-in-one SEO AI detection tool, check out Kazan SEO.
Kazan SEO is another entirely free tool with the ability to detect GPT-2, GPT-3, and ChatGPT content quickly.
This neat toolkit has multiple features outside of AI detection, including a content generator, a tool for discovering and researching keywords, URL text extraction for SEO analysis, and co-relational content optimization.
If you need more than just AI detection, we recommend Kazan SEO for its wide variety of SEO tools.
Note: you do have to make an account to use this tool.
How We Chose Our Favorites (Ranking Metrics)
We looked at a few things when choosing our list of favorites.
Accuracy and Reliability
First and most importantly, we looked at how accurate and reliable each of these checkers was at detecting ChatGPT content consistently.
False Positive/Negative Rates
Hand-in-hand with accuracy, how often each detector falsely identified AI content as human-written and vice versa was studied carefully.
Speed/Efficiency
Since we don’t have all day to wait on a checker, we cut all of the free AI detectors that took too long to load results.
Reviews
We looked at other people’s experiences with each of these detectors to make sure others had positive experiences, too.
How to Beat ChatGPT Detectors?
Beating a detector is the wrong target, since Google isn't running one against you. But the same steps that lower a detector score also make the article better, so it's worth doing.
First, run your ChatGPT-generated content through one of these detectors to get a good read on how human it sounds and which specific sentences sound too “computer-y.”
Then, it’s always a good idea to get a human pair of eyes on your content. An editor can reword and reformat anything that doesn’t flow naturally and add personality to the content before you publish it.
ChatGPT Watermarking
A cryptographic “watermark” is rumored to be making its way onto ChatGPT content that will make it easier to identify ChatGPT content.
This watermark would be the text equivalent of an image or video watermark which would entail embedding a sort of code into the content through word choice and punctuation.
But why would OpenAI do this?
The reason for the watermarking is to ensure that ChatGPT content is used ethically and in alignment with OpenAI’s stance and commitment to AI safety.
OpenAI’s stance on AI safety is that “The goal of long-term artificial intelligence (AI) safety is to ensure that advanced AI systems are reliably aligned with human values — that they reliably do things that people want them to do.”
In other words, the ChatGPT watermarking feature would ensure that ChatGPT content isn’t misused in a way that could be seen as detrimental to humanity.
There will be ways to defeat this feature. For example, if you take ChatGPT content and run it through another AI writing service, the information will be scrambled and reformatted, erasing the watermark.
FAQs
How accurate are AI detector tools?
AI detector tools are not very accurate just yet and are only able to identify around 25%-50% of AI-generated content as “likely AI-written”.
What is the best AI detector for ChatGPT output?
Sapling, of the free ones. Content at Scale's detector used to hold this spot, but the company became BrandWell and retired it. If you can pay, Originality.AI is the most dependable we have used.
Is ChatGPT output detected by Google?
Google has never said it detects or demotes ChatGPT output for being AI-written. It judges whether a page is useful. A thin, generic article will struggle whether a person or a model wrote it.
