Undetectable AI vs Grammarly: Which One Fits You Better

If we’re talking pure writing assistants, none have come close to the popularity of tools like Grammarly and QuillBot. They’ve become staples in the writing and education community since they’re among the first to address two of the biggest issues at the time: readability and plagiarism.

However, we’re now shifting to a new era — one where anyone can generate entire essays from just a single prompt. This has caused people to panic, especially educators and employers, and start using AI detection tools. The problem is that they’re not always accurate.

And that’s when Undetectable AI entered the picture. It’s been an effective weapon against false positives in the AI writing space.

But, if we were to put the old and the new in a head-to-head battle, which one would come out on top? In this article, I’ll be comparing Undetectable AI against Grammarly, and decide once and for all, which one should you get.

What is Undetectable AI and Grammarly?

Undetectable AI is one of the best AI bypassers in the market. It’s made to humanize AI-generated text by removing common AI markers and intentionally adding human errors to simulate human writing. Undetectable AI also has other features such as an AI human typer (which we’ve already reviewed) and a collection of AI detection tools.

Grammarly, on the other hand, is somewhat different. It’s one of the most popular online grammar checking, spell checking, and plagiarism detection platforms. Grammarly’s most popular feature is its paraphraser, a web-based application that uses natural language processing to remove any grammar issues and improve your text’s overall coherence.

Undetectable AI vs. Grammarly: Features

Undetectable AI’s most important feature is AI bypassing or humanizing AI-generated text so that it becomes unrecognizable to detectors. Other than that, Undetectable AI has output customization features which can be divided into the purpose, readability, and balance level.

For readability level, you can choose between:

• High School: Simple and comprehensible text for everyone.
• University: Similar to text you’ll find in a college textbook.
• Doctorate: Most complex and will use a lot of complicated words to get your point across.
• Journalist: Meant for news articles and other similar documents.
• Marketing: Made for marketing copies and social media marketing content.

For purpose, you have the following choices: general writing, essay, news article, marketing or legal material, story, cover letter, report, or business material.

And for balance, here are your three options:

• More Readable: Clearest but most likely to be marked as AI-generated
• Balanced: Readable but removes common AI identifiers. This still often gets tagged as AI-generated in my experience.
• More Human: Removes all AI identifiers and adds intentional errors to your text.

Grammarly is a little different from most paraphrasing tools. Once you open a new document using their app, you’ll be greeted with these:

These goals influence how Grammarly will assist you in writing. Another thing you should know about Grammarly is that it doesn’t normally (there’s a solution for this, which we’ll get to later) rephrase the entire text for you. Instead, it highlights specific parts of the document that need improvement and lets you have full control over how you want it to be phrased. 

For example:

There’s also an overall score on the right side of their web app. This tells you the readiness of the article in regards to its grammar and readability. Once you’ve implemented everything Grammarly suggests, the score goes up to 100.

One last thing you can do is press the “Generative AI” button below the goals option. A chat popup should appear on the lower right side of your screen. If you’re pressed for time, you can just let the generative AI rephrase the entire document for you and call it a day. This is what we’ll test in the later parts of this article.

Undetectable AI vs. Grammarly: Output Quality

This comparison won’t be complete without comparing the readability of documents from Undetectable AI and Grammarly. Below are three texts: one is the original GPT-generated essay and the other two are from our competitors today.

Right off, I could already tell that Grammarly rewrote the original text better. Their rewritten version sounds smooth without any grammar mistakes or missed punctuations. One thing I appreciate about it the most is that it’s contextual rewriting — sure, there are some instances where Grammarly just took the synonym of a word, but it’s mostly rephrased in such a way that it becomes different to the original text, but still has the same message.

As for Undetectable AI, it’s a completely different story. It’s riddled with misplaced punctuation marks and grammar errors that could be easily fixed. However, it’s worth noting that Undetectable AI has to contain those mistakes because it’s one way to avoid AI detection. 

All in all, this round goes to Grammarly, no question.

Undetectable AI vs. Grammarly: AI Detection

Test #1

Undetectable AI Successful!
AI Likelihood Score: 0.0%

Grammarly Unsuccessful.
AI Likelihood Score: 100.0%

Test #2

Undetectable AI Successful!
AI Likelihood Score: 0.1%

Grammarly Unsuccessful.
AI Likelihood Score: 100.0%

Test #3

Undetectable AI Successful!
AI Likelihood Score: 0.0%

Grammarly Unsuccessful.
AI Likelihood Score: 100.0%

Test #4

Undetectable AI Successful!
AI Likelihood Score: 0.0%

Grammarly Unsuccessful.
AI Likelihood Score: 100.0%

Test #5

Undetectable AI Successful!
AI Likelihood Score: 38.2%

Grammarly Unsuccessful.
AI Likelihood Score: 100.0%

Test #6

Undetectable AI Successful!
AI Likelihood Score: 0.8%

Grammarly Unsuccessful.
AI Likelihood Score: 100.0%

Overall Scores

The Bottom Line

Often when we’re comparing two tools, we’re too focused on asking “which is better?” But that’s not always the right question. For Undetectable AI and Grammarly, the question should be: Which one fits your needs better?

Grammarly and Undetectable AI exist for completely different reasons. The former was built to be a true writing assistant for students and writers. It’s made to avoid grammar mistakes and ensure your writing doesn’t include any accidentally plagiarized content. The latter, on the other hand, was built to fight against false positives in the AI detection space.

So, the question you should be asking yourself is what is it really that you need.

At the end of the day, both these paraphrasing tools are incredibly effective at what they do. Just make sure you pick the right one for your use case and you’re good to go. But before you do, I highly encourage you to read some of our articles on Undetectable AI like this one to get a better picture of its effectiveness. Good luck!