Grammarly AI Detector vs a Free AI Checker
By AIDetector365 Editorial Team · 12 min read · Published · Updated
Grammarly is often the first name people type when they want an AI detector or AI checker. That is not an accident: Grammarly already sits in millions of browsers as a grammar tool, and it added AI detection on top of that audience. The search is usually practical: “Does Grammarly flag this as AI?” — not a request for a brand recap.
This article separates Grammarly’s grammar product from its AI detector, compares both with a free in-browser checker and says when Grammarly is the better fit. If you only need a private check, use the free AI checker.
Key takeaways
- Grammarly’s grammar checker and its AI detector are different products that people search as if they were one.
- Grammarly’s detector is useful if you already live in Grammarly; it still cannot prove authorship.
- A free browser checker is the better default when you do not want an account or an upload.
- Run grammar cleanup and AI detection as two steps. Fixing commas does not settle an AI question.
- Vendor accuracy claims are measured on clean samples; mixed school and work writing is harder.
Try it now: Free AI Checker
Free AI checker to see if text was written by ChatGPT or other AI. Instant sentence highlights, no login, runs in your browser.
Two Grammarly searches, two jobs
“Grammarly” on its own is mostly a grammar and spell checker. “Grammarly AI detector” and “Grammarly AI checker” are about whether the writing looks machine-generated. Mixing them leads to a common mistake: someone runs Grammarly, accepts tone suggestions and then treats a later AI score as independent evidence — even though the text has just been smoothed toward a more uniform voice.
| Grammarly grammar | Grammarly AI detector | AIDetector365 | |
|---|---|---|---|
| Main job | Spelling, grammar, clarity, tone | Estimate if text looks AI-written | Estimate if text looks AI-written |
| Typical search | grammarly, spell check | grammarly ai detector / checker | ai checker free, ai detector |
| Account | Yes for full features | Yes, inside Grammarly | No |
| Where text goes | Grammarly’s service | Grammarly’s service | Your browser only |
| Sentence reasons | Grammar suggestions | AI highlighting (product-dependent) | Highlight plus a reason per sentence |
| Plagiarism | On paid plans | Not the same as AI detection | No |
| Cost | Free tier + Premium | Part of Grammarly’s plans | Free |
Plans and feature names change. Check Grammarly’s site for what your account includes. For grammar-only help on this site, use the grammar checker.
What Grammarly’s AI detector is good at
If you already draft in Grammarly, checking AI signals in the same sidebar is convenient. Teams that standardize on Grammarly get one login, one browser extension and a familiar report. That workflow matters more than a two-point difference on a synthetic accuracy chart.
It is a weaker fit when you need to paste someone else’s work without creating a document in their cloud, when you want the text to stay on the device, or when you are comparing two detectors on the same sample. Grammarly is also a writing assistant: its own suggestions can make human prose look a little more “even,” which is one of the textures detectors watch for.
Grammarly vs GPTZero vs a free checker
A wider round-up of free options is in Best free AI detectors compared. None of them, including Grammarly, should be the only evidence in a misconduct case. Independent studies keep finding that detectors stumble on short, edited, formal and non-native English writing — details in How accurate are AI detectors?.
| If you need… | Start with |
|---|---|
| Grammar and AI in one familiar extension | Grammarly |
| Classroom batch checks and writing-process reports | GPTZero (see GPTZero vs Copyleaks) |
| A second opinion without an account | Free AI checker |
| Essay-shaped guidance | AI detector for essays |
How to compare Grammarly with a free checker yourself
If the two tools agree on the raw ChatGPT sample and disagree on the edited one, that disagreement is information: the evidence is weak, not that one vendor is “broken.”
- Save three samples you know: a paragraph you wrote, a raw ChatGPT answer and the ChatGPT answer after you edited it.
- Use 300+ words each.
- Run each sample through Grammarly’s AI detector (if your plan includes it) and through the free AI checker.
- Write down the label, not only the number, and which sentences were flagged.
- Look hardest at the edited sample. That is the case most people actually have.
Privacy and student work
Grammarly processes text on its servers so the extension and editor can work. That is reasonable for your own email. It is a different decision for unpublished research, client copy or a student’s take-home exam. Read Grammarly’s product terms before you paste work that is not yours.
AIDetector365 takes the opposite trade: no account, no upload, no plagiarism index. You get a private AI check and you give up institution-wide reporting. For a quick personal check, that is usually the point.
Frequently asked questions
Does Grammarly have an AI detector?
Yes. Grammarly offers AI detection as part of its writing platform. Availability depends on the plan and the current product. It is separate from spelling and grammar suggestions.
Is Grammarly’s AI checker free?
Grammarly has a free tier for writing help. AI detection may sit behind a paid plan. Check Grammarly’s pricing page. AIDetector365’s AI checker is free with no login.
Can Grammarly detect ChatGPT?
It can flag text that looks like typical large-language-model writing, which includes ChatGPT. It cannot prove ChatGPT was the source, and heavy editing reduces the signal.
Is Grammarly an AI detector or a grammar checker?
Both, as separate features. “Grammarly” in search usually means grammar; “Grammarly AI detector” means the AI score. Do not treat a grammar pass as an AI verdict.
What is a free Grammarly AI checker alternative?
AIDetector365’s free AI checker runs in your browser, highlights sentences and does not require an account.
Put this into practice: Free AI Checker
Free AI checker to see if text was written by ChatGPT or other AI. Instant sentence highlights, no login, runs in your browser.