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Free Grammar Checker
Fix grammar and spelling, fully private|4.8 (1,087)
A free, private grammar checker that corrects grammar, spelling, and punctuation without sending a single word to any server. It is built on WebLLM (MLC AI), the open-source engine that runs full large language models directly in your browser using WebGPU for hardware acceleration. Under the hood it loads Meta Llama 3.2, a modern instruction-tuned model, and runs it entirely on your own GPU. Paste an email, an essay, a message, or any text, choose to either correct mistakes only or correct and lightly improve readability, and the model returns the cleaned-up version on-device. Because every token is generated locally, your text is never uploaded, logged, or stored. The model downloads once on first use and is cached by your browser, and it is the same model shared by the other in-browser AI tools, so it is ready instantly after the first download.
Free and provided as is, without warranty. Use at your own risk. Terms
Check grammar online without sending it anywhere
Most online grammar checkers upload your text to a server, run it through a hosted model, and send the corrections back, which means your content leaves your control the moment you paste it in. This free grammar checker takes the opposite approach: the language model itself runs inside your browser tab. Once the model is downloaded, every correction is generated on your own device, so the email, essay, or private note you paste never touches a server.
That privacy model makes it a strong fit for sensitive material such as confidential emails, legal text, client communications, or unpublished writing, where pasting content into a cloud AI service is not acceptable. You get clean, corrected output with the same privacy guarantees as an offline app, and you can verify there is no upload by watching the Network tab in your browser DevTools while you work.
Powered by WebLLM and Llama 3.2, running on your own GPU
This tool is built on WebLLM, the open-source project from MLC AI that brings full large language models to the web: it compiles models to run directly in your browser using WebGPU for hardware acceleration, with no backend server involved. The model executes on your own graphics hardware, which is what makes private, local grammar correction practical in an ordinary browser tab.
For grammar checking it loads Meta Llama 3.2, a modern instruction-tuned model that follows correction instructions well at a size small enough to run client-side. The roughly 800MB of quantized weights download once, are cached by your browser, and are shared with the other in-browser AI tools on this site, so there is no repeat download when you move between them. WebLLM is released under the permissive Apache 2.0 license.
How AI grammar correction works and tips for better results
A language model corrects text differently from a rules-based checker: instead of matching a fixed list of grammar rules, it predicts the most likely correct version of your sentence based on patterns it learned from large amounts of writing. That makes it good at context-dependent fixes, such as the right verb tense, subject-verb agreement, article use, and punctuation, that simple checkers often miss. The tradeoff is that a model can occasionally over-correct or leave your wording slightly changed, so a quick read of the result is always worth it.
For the cleanest corrections, use the Correct mode when you want minimal edits that only fix clear mistakes, and Correct & improve when you also want awkward phrasing smoothed out. Keep each request to a paragraph or a few paragraphs so the model can attend to the whole passage, and paste plain prose rather than fragmented notes or code. Because the model preserves the original language, it is also useful for tidying up writing in a second language without translating it.
Who reaches for a grammar checker, and when
Non-native English speakers use it to catch article and preposition mistakes, the "a" versus "the" and "in" versus "on" errors that are genuinely hard to internalize as a second language, before sending a work email or submitting an assignment. Students proofread essays and cover letters, and professionals give a final pass to a client-facing message or a report before it goes out, catching the kind of small mistake that undermines an otherwise solid piece of writing.
It also gets used on text that is not really "writing" in the traditional sense: cleaning up a rough voice-to-text transcript, tidying punctuation in notes pasted from a meeting, or fixing capitalization in text extracted from a scanned document via OCR, all cases where the source text is messy for reasons that have nothing to do with the writer's grammar skill.
How this compares to Grammarly and LanguageTool on cost
Grammarly's free tier covers basic spelling and grammar, but its more advanced tone and clarity suggestions sit behind Grammarly Premium, which runs roughly 12 to 30 dollars a month depending on the billing plan, and every check is processed on Grammarly's servers. LanguageTool is a genuinely good open-source, rules-based alternative with a generous free tier, though its premium style suggestions are also a paid add-on, typically 5 to 20 dollars a month.
This tool has no tier at all: every feature, including the "improve clarity" mode, is available for free because the model runs on your own GPU instead of a server you would otherwise be paying for indirectly through a subscription. The tradeoff is that a large commercial grammar service can offer richer style coaching and tone analysis built on far more specialized training than a general-purpose local model provides.
What an AI grammar checker catches, and where a human still wins
A language model is genuinely good at the errors that depend on context: subject-verb agreement across a long sentence, the correct verb tense given the surrounding paragraph, and awkward phrasing that a simple rule can't flag because nothing is technically "wrong," it just reads poorly. That is a real advantage over older rules-based checkers, which are excellent at spelling and simple agreement but blind to anything requiring actual comprehension of the sentence.
The honest limitation is the same one every language model has: it can occasionally rewrite a phrase you meant to keep, or miss a subtle factual or logical issue that isn't a grammar problem at all. Treat the output as a strong first pass, not a final authority, especially for anything going to a client, a publisher, or an academic reviewer, where a careful human read-through before sending still catches things no automated checker will.
How It Works
Click "Load model" once to download the Llama 3.2 language model into your browser via WebGPU, then paste or type the text you want to check.
Choose a mode: Correct fixes only the mistakes, while Correct & improve also smooths awkward phrasing.
Click Fix grammar and watch the corrected text stream in, then copy it to your clipboard or download it as a text file.
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Key Features
Privacy & Trust
Use Cases
Limitations
- Requires a browser and device with WebGPU support (recent Chrome, Edge, or Brave on a desktop with a capable GPU); browsers without WebGPU cannot run the model
- The first run downloads roughly 800MB of model weights, which can take a few minutes on slower connections, though it is cached by your browser afterward
- As with any language model, it can occasionally miss an error or change wording you intended to keep, so review the corrected text before relying on it
- Generation speed depends on your GPU: it is fast on a modern discrete GPU and slower on older integrated graphics or mobile devices
Frequently Asked Questions
Is this grammar checker really free?
Yes, it is completely free with no signup, no account, and no usage limits. Because the language model runs on your own GPU through WebLLM instead of a paid cloud API, there are no per-request costs to pass on. You can check as much text as you want, as often as you want, without a credit card, an API key, or a rate limit.
Is my text sent to a server when I check it?
No. The entire grammar-checking process runs locally in your browser using WebLLM and WebGPU. After the model is downloaded once, every correction is generated on your own device with zero network requests carrying your text. Your content is never uploaded, logged, stored, or seen by anyone, which makes this safe for confidential emails, internal reports, and private documents that should not touch a cloud service. You can confirm this by opening the Network tab in your browser DevTools while you use it.
Do I need to install anything to use it?
No installation is needed. It is a pure web tool that runs in any modern browser with WebGPU support. The only thing that downloads is the Llama 3.2 model itself, which WebLLM fetches on first use and caches in your browser. There is no extension, no desktop app, and no Python or Node environment to set up.
Which model does the grammar checker use and how big is it?
It uses Meta Llama 3.2, an instruction-tuned language model compiled for the browser by MLC AI and run through the WebLLM engine on WebGPU. The quantized weights are roughly 800MB and download once on first use, then are cached by your browser. It is the same model used by the in-browser AI chat and paraphrasing tools, so if you have used those, the grammar checker loads instantly with no extra download.
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