Justdone AI Review: Testing AI Detector, Humanizer, and More

Turnitin's official press release published on February 24, 2026, reports that an average of 14.8% of English-language submissions to the latest version of its AI detection tool contained 80% or more AI-generated writing between October 2025 and February 2026. This number has increased more than fourfold since 2023, when the average of English-language submissions was 3.3%.

This trend has increased the demand for not just AI detectors and plagiarism checkers, but AI humanizers as well. Students and content creators are becoming aware that their AI-written submissions can be caught easily, so they are looking for tools made to humanize AI-written text.

Some platforms bundle all these tools in a single package to attract users from all sides. 

Justdone is one of those platforms. It offers the three tools mentioned above as its core services.

My job is to test whether the said tools perform as advertised and are worth using.

And that’s what I have done in this Justdone AI Review. I tested each of Justdone's three core tools separately to see how well they hold up.

Let’s start with an overview of the platform.  

What is Justdone AI?

Justdone is an AI-powered writing assistance and productivity platform made for students, educators, content creators, marketers, etc.

It offers over 100 AI tools across 11 categories such as:

• AI citation tools
• AI creativity
• AI emails
• AI business
• AI productivity
• AI for social media
• AI detection 
• AI translation
• Summarizing
• Grammar checking
• AI writing

Out of all its tools, Justdone is known for its plagiarism checker, AI humanizer, and the AI detector. These are the tools that Justdone markets prominently on its website.

According to Justdone, these three tools are double-checked by GPTZero, Originality.ai, and Scribbr. It’s not clear what is meant by that exactly. If we take the AI humanizer for example, this claim could mean that the humanized content bypasses the aforementioned AI detectors. But does it? You’ll find out in the review below.

Justdone allows you to use these tools for free but with a very small amount of text at a time. For example, the AI detector allows 80 words/scan only on the free plan, which isn’t enough for almost any use case.

You have to buy the paid plan to unlock higher word limits along with other premium features.

In my testing, I found that Justdone tools on a free plan tend to produce inaccurate results for some unknown reason. The tools on the free plan also run into some technical issues that you don’t face on the premium plan.

Let’s start the Justdone review, where I’ll elaborate on my hands-on experience testing its tools. 

How I Tested Justdone AI Tools

As you read, Justdone offers over 100 tools, but only three of them are the primary focus of the platform, namely, the AI detector, AI humanizer, and plagiarism checker. 

So I’ll stick to these three tools in this Justdone AI review. 

The testing methodology will be similar to what I have been following in reviews of other similar platforms.

Here’s a brief description of the testing methodology I followed for each of the three tools:

• AI detector: Generated a total of 6 fully AI-written samples with Claude, ChatGPT, and Gemini (2 samples from each). Also used 7 fully human-written samples from before 2020 when there were no commercial generative AI tools like ChatGPT.
• AI humanizer: Generated text with ChatGPT, humanized it using Justdone twice with different settings, and checked the output using GPTZero and Justdone’s own AI detector. 
• Plagiarism checker: Gathered several types of content published online starting from the past month (July, 2026) and going as far back as 1996. The mix of samples included news articles, academic papers, video transcripts, etc.

I purchased the 7-day trial of Justdone Premium to get access to a full range of features. Let’s start with my Justdone AI detector review.

Testing Justdone AI Detector

Earlier, when I said that Justdone’s free plan and premium plan function very differently, I was mainly talking about its AI detector.

I tested the Justdone AI detector both on the free and paid plans. The difference in the accuracy of the two tools was enormous. The free plan gave inaccurate AI detection results and also ran into some technical issues.

For instance, there’s a limit of 80 words/scan on the free plan. But the AI detector lets you paste text far longer than that and even checks it for AI when you click the button without warning you about the word limit.

Here’s an example of a fully AI-written text I scanned for free:

When I scanned the same AI text with the paid AI detector, Justdone flagged it as 100% AI. Good, but it should also have been flagged as 100% AI when I scanned it using the free detector.

I scanned all the AI and human samples (6 fully AI-written and 7 fully human-written) on both the free plan and the premium, and the free plan produced inaccurate results every time. In contrast, the premium AI detector would be accurate.

There was another problem with the free Justdone AI detector. Every subsequent AI scan would repeat the same AI percentage from the previous AI scan. This issue wouldn’t resolve even if you hard refresh the website by pressing Ctrl + Shift + R or Cmd + Shift + R.

The premium plan had none of these issues. Whatever the cause, the effect is that you can not rely on the free detector's output. If you're using or evaluating Justdone, test with the paid version.

All said, the paid AI detector reported accurate AI scores for most of the AI and human-written samples. Only three samples had a slight error.

Here’s the summary of AI scores that the Justdone AI detector reported for the 100% AI samples:

And here are the AI scores of Justdone AI detector reported for the 100% human samples:

To see my testing, including all detection screenshots of AI and human-written samples, please see this PDF document.

Testing Justdone AI Humanizer

The point of testing Justdone’s AI humanizer was to see whether it can bypass AI detectors or even lower the AI score because that’s essentially the job of these humanizer tools.

Here’s the text that I generated with ChatGPT to give to Justdone’s AI humanizer.

Then, I copied the text ChatGPT generated and gave it to the Justdone AI humanizer. Justdone lets you choose the tone for the resulting humanized text based on the purpose of the text. The given options are:

• Auto
• Sound human
• Bypass detectors 

The default tone is set to Auto, and I left it at that for this time. You can read the text it humanized on the right:

Next, I scanned the text for AI using GPTZero’s AI detector, and it reported a 100% AI score. So Justdone couldn’t lower the AI score by a single percentage point, let alone bypass AI detection.

GPTZero could even tell that the pasted text was an AI-humanized version of an original AI text.

The Justdone AI humanizer lets you run an AI scan on the humanized text using its own AI detector. So I tried that, too, and it reported a 0% AI score, which is of course inaccurate.

It’s surprising that the same AI detector that performed accurately on a bunch of AI- and human-written samples would fall for AI-humanized text.

One could say that this seems like a marketing ploy. The AI detector might be designed to deliberately report a low or 0% AI score for the humanized text to sell the AI humanizer.

But I, personally, don’t think that’s the case here.

Because this could very well be the result of the inaccuracy of Justdone’s AI detector against AI-humanized text. The AI detector may simply not be trained, intentionally or not, to perform accurately on AI-humanized text.

This doesn’t change the fact that advanced AI detectors like GPTZero can accurately call out text humanized by Justdone.

I gave Justdone AI humanizer another chance and switched the tone to “Bypass Detectors,” but the humanized text could still not bypass GPTZero.

GPTZero flagged it as 100%, with the verdict that the text was originally AI and rewritten by AI, which is true. So, in short, Justdone AI Humanizer failed to bypass GPTZero.

You can read this PDF if you want to see my full testing of Justdone AI Humanizer.

Now, it’s time for the Justdone plagiarism checker review.

Testing Justdone Plagiarism Checker

I also tested the Justdone plagiarism checker using 10 plagiarized samples from around the web, dating as far back as 1996.

The accuracy was very high on all samples except one. That one sample was given a 13% plagiarism score despite the text being the transcript of a YouTube video published in 2018.

Apart from that, all samples were accurately caught as plagiarized with high scores and traced back to their respective sources.

It was impressive to see that Justdone could detect plagiarism from niche company websites like Sage.

My only complaint is that the detailed plagiarism report should be displayed right there on the webpage. Currently, you must choose between downloading it or getting it sent to your email. Also, the tool can sometimes take forever checking text for plagiarism.

Here’s how Justdone plagiarism checker scored all 10 samples:

To see my testing results with all the screenshots, refer to this PDF.

How Much Does Justdone Cost?

Justdone offers a single paid plan that unlocks access for all its tools. 

You can either buy the monthly or annual plan.

A 7-day paid trial of this plan is also available, which automatically subscribes you to the monthly plan when the trial ends. Users must cancel the trial 24 hours before it ends if they want to avoid the automatic charge.

I find it strange that the monthly plan costs $19.99 when purchased directly but costs $29.99 when you’re using the paid trial.

The unlimited annual plan costs $119.88/year, which is $9.99/month. 

GPTZero’s AI Detection & Plagiarism Checking is Far More Accurate

While Justdone’s AI detector and plagiarism checker were highly accurate in my testing, they were still slightly off the mark in a few instances.

Not to mention, the AI detector gave a 0% AI score to the AI-humanized text, which calls the AI detector's accuracy into question.

But GPTZero’s AI detector was 100% accurate every single time. It reported perfectly accurate AI scores for AI-written, human-written, and humanized text. GPTZero could also tell when an AI-written text sample was paraphrased by AI.

GPTZero’s plagiarism checker also has a high accuracy rate. It even generates citations for the plagiarized text for when you want to ethically quote text from an external source.

Try GPTZero for free today and witness the accuracy yourself.