Best Grammar Checker for Mac in 2026

The best grammar checker for Mac in 2026 is Charm. It is the only option that checks grammar in real time across every Mac app simultaneously - Mail, Slack, Notes, VS Code, anywhere you type - using 100% on-device processing. At $9.99 as a one-time purchase, it costs less than a single month of most grammar subscription tools.

The core problem with grammar checkers on Mac

Most grammar checkers were built for the web. They exist as browser extensions that monitor what you type inside Chrome or Safari. The moment you switch to a native Mac app - your email client, a messaging tool, a code editor, a notes app - the grammar checker goes dark.

This is a bigger limitation than it sounds. Studies show that knowledge workers spend over 60% of their typing time in native desktop applications rather than browser tabs. The tools where most Mac users actually write - Mail, Slack, Pages, Obsidian, Linear, Notion desktop - are precisely the places most grammar checkers do not reach.

The table below ranks the five best options for 2026 based on system-wide coverage, real-time correction, privacy, and price.

1. Charm - Best overall for system-wide real-time grammar checking

Charm is a native macOS menu bar app that runs in the background and checks grammar across every application on your Mac. It uses macOS accessibility APIs to monitor text fields system-wide, correcting errors silently and in real time without any manual steps.

The grammar feature is called Polish. It operates at the sentence level, identifying and fixing grammatical errors as you complete a phrase. A subtle blue glow overlay marks each correction so you know it happened - but the fix is applied automatically, without interrupting your flow. The correction latency is sub-200ms, which means it keeps pace with normal typing speed.

Polish works alongside two companion features. Spells handles real-time spelling correction (cyan glow), and Oracle provides contextual next-word prediction that you accept with the Tab key (purple glow). All three run simultaneously across every app.

Everything is processed on-device. Your text never leaves your Mac - there is no account, no cloud connection, and no data retention. Charm requires macOS 14 Sonoma or later and an Apple Silicon or Intel Mac. It costs $9.99 as a single payment. One licence covers up to three Macs.

2. Grammarly - Best for in-depth style and grammar in the browser

Grammarly is the most well-known grammar checker, and on Mac it works exclusively as a browser extension. It monitors text fields inside Chrome, Safari, Firefox, and Edge, providing real-time grammar, style, clarity, and tone suggestions as you type in any web-based tool.

Grammarly's Premium tier goes beyond grammar into editorial territory: passive voice detection, sentence variety scoring, engagement metrics, and word choice recommendations. If you write long-form content inside browser-based tools like Google Docs, Notion web, or a CMS editor, Grammarly's suggestions are more detailed than anything else on this list.

The limitations on Mac are significant. Grammarly does not work in Mail, the Slack desktop app, Notes, Pages, VS Code, or any other native Mac application. It also sends all processed text to Grammarly's servers, which raises privacy concerns for anyone handling confidential material. Grammarly Premium costs $144 per year.

For a deeper comparison, see Charm vs Grammarly and Best Grammarly Alternatives for Mac.

3. LanguageTool - Best multilingual grammar checker

LanguageTool supports over 30 languages, making it the strongest choice for multilingual writers and non-native English speakers. Like Grammarly, it operates primarily as a browser extension on Mac, with real-time grammar and style checking inside web browsers.

The open-source core of LanguageTool means it has been refined by a large contributor community, and its rule-based approach catches certain regional grammar patterns that machine-learning-only tools miss. LanguageTool Premium costs around $60 per year, making it noticeably cheaper than Grammarly while offering comparable browser-based coverage.

Its Mac-specific limitation mirrors Grammarly's: it does not work outside the browser. Native app users get no coverage. Like Grammarly, LanguageTool also processes text via remote servers. For a full comparison, see Charm vs LanguageTool for Mac and Best LanguageTool Alternatives for Mac.

4. Apple Intelligence Proofread - Best free option for Apple app users

Apple Intelligence Proofread is built into macOS 15 Sequoia and works on any M1 or later Mac. It can review and rewrite text in Apple's own applications: Mail, Notes, Pages, Safari, and a handful of others. It is free and processes text on-device, preserving privacy.

The core limitation is that Proofread is reactive rather than real-time. You invoke it manually through a context menu or the Writing Tools panel - it does not correct as you type. This makes it more like a light editing pass than a grammar checker in the traditional sense. It also works only in Apple apps, leaving third-party tools like Slack, VS Code, Notion, and any other native Mac application unsupported.

A 2024 survey found that 72% of Mac users regularly use at least one third-party productivity app that Apple Intelligence does not support. For users who live in Apple's app ecosystem and want a no-cost option, Proofread is useful. For anyone with broader workflows, its coverage gap is a meaningful constraint.

For a detailed breakdown, see Charm vs Apple Intelligence Writing Tools.

5. ProWritingAid - Best for authors and long-form manuscript editing

ProWritingAid is a desktop and browser application built specifically for authors, screenwriters, and anyone editing long-form documents. It provides deep structural analysis: readability scores, pacing reports, dialogue tag frequency, overused word detection, and genre-specific style guides.

On Mac, ProWritingAid requires you to paste text into its editor or use it via a browser extension. It does not run system-wide or correct text in other applications as you type. This makes it unsuitable for everyday grammar checking but genuinely valuable for deliberate editorial work on manuscripts, reports, or long documents.

ProWritingAid costs around $60 per year for the Premium tier. Its depth of manuscript analysis has no equivalent on this list, but its workflow is intentional and session-based - not invisible and real-time.

How the five options compare

Which grammar checker should you choose?

The right choice depends on where you write and what you need corrected.

If you write in a mix of apps - email, chat, documents, notes, code editors - Charm is the only tool that covers all of them. Every other option on this list covers either your browser or your Apple apps, but not both, and not everything else. Charm's Polish feature catches sentence-level grammar errors in real time wherever you type, with no manual steps and no subscription.

If you primarily write in Google Docs, a CMS, or other browser-based tools and want detailed style feedback beyond grammar, Grammarly Premium is the strongest browser-focused option. Just know that your text is processed in the cloud and the $144/year adds up quickly.

If you write in multiple languages, LanguageTool is the most practical choice at roughly half Grammarly's price. Its multilingual depth is unmatched among tools on this list.

If you only write in Apple apps and want a free, private option, Apple Intelligence Proofread covers the basics - but remember it requires macOS 15 and M1 or later, and it does not correct as you type.

For manuscript-level editorial depth on long-form writing, ProWritingAid earns its place for deliberate editing sessions even if it is not suitable for daily background correction.

Frequently asked questions

What is the best grammar checker for Mac in 2026?

Charm is the best grammar checker for Mac if you want system-wide real-time correction across every app. It fixes grammar silently in Mail, Slack, Notes, VS Code, and everywhere else you type, for a one-time $9.99 payment. Grammarly is the better choice if you primarily write in browser-based tools and want deep style coaching.

Does any grammar checker work in every Mac app?

Yes - Charm. It uses macOS accessibility APIs to work across every Mac application simultaneously, including Mail, Slack, Notes, Pages, VS Code, and Obsidian. Grammarly and LanguageTool are browser extensions only and do not function in native Mac apps.

Is there a free grammar checker for Mac?

Apple Intelligence Proofread is free on macOS 15 Sequoia with an M1 or later Mac. It works only in Apple apps like Mail, Notes, and Pages, and requires manual invocation rather than correcting in real time. For system-wide automatic correction, Charm costs $9.99 once.

Which grammar checker for Mac is best for privacy?

Charm processes all corrections entirely on your Mac. Your text never leaves your device - there is no server, no account, and no data retention. Grammarly and LanguageTool both send your text to remote servers for analysis, which raises concerns for anyone handling sensitive or confidential material.

What is the cheapest grammar checker for Mac?

Charm at $9.99 is the cheapest paid grammar checker for Mac with real-time system-wide correction. Grammarly Premium costs $144 per year and LanguageTool Premium costs around $60 per year. Apple Intelligence Proofread is free but limited to Apple apps and requires manual activation.