Autocorrect and Grammarly are not the same type of tool, which makes "which is better" a misleading question. Autocorrect is a feature category - real-time dictionary-based spelling replacement - that appears in macOS, Charm, and Grammarly itself. Grammarly is a specific product that adds grammar, style, and tone analysis on top of spelling correction. The real question for Mac users is: which tool covers the apps you actually write in?
What does each tool actually do?
macOS autocorrect is the built-in system. It replaces misspelled words as you type using a dictionary-based model. It works in native Mac apps - Pages, Mail, Notes, TextEdit, Messages - but not in browser-based apps or Electron apps like Slack, VS Code, or Notion. It offers no grammar checking, no style suggestions, and no word prediction. It is free and requires no configuration to get started.
Grammarly is a writing tool that installs as a browser extension and optionally as a desktop app. The browser extension works inside Chrome, Safari, and other browsers - which means it covers Gmail, Google Docs, Notion web, LinkedIn, and any other web-based writing surface. The desktop app adds a floating panel that can check documents across some apps. Grammarly's free tier covers spelling and basic grammar. Premium (at $144/year) adds style analysis, tone detection, clarity suggestions, and plagiarism checking.
The significant limitation: the browser extension alone only covers text inside the browser. Desktop apps such as Mail, Word and Slack need Grammarly's separate Mac app, and in both, every fix is a suggestion you have to accept.
Charm is a native macOS app that sits at the operating system level. It uses the Accessibility API to reach text fields in every type of application - native, web app, and browser - and provides spelling correction (Spells), grammar correction (Polish), and word prediction (Oracle), all automatic as you type. It processes everything on-device. It costs $19.99 once.
How do they compare head to head?
| Feature | macOS Autocorrect | Grammarly Free | Grammarly Premium | Charm |
|---|---|---|---|---|
| Native Mac apps | Yes | Supported apps (Mac app) | Supported apps (Mac app) | Yes |
| Browser (Google Docs etc.) | No | Yes | Yes | Yes |
| Electron apps (Slack, VS Code) | No | Slack yes, VS Code no | Slack yes, VS Code no | Yes |
| Grammar correction | No | Basic | Advanced | Yes |
| Style suggestions | No | No | Yes | No |
| Word prediction | No | No | No | Yes |
| On-device processing | Yes | No | No | Yes |
| Works offline | Yes | No | No | Yes |
| Price | Free | Free | $144/year | $19.99 once |
Which tool should you use - and when?
The answer depends on two factors: where you write and what level of correction you need.
If you write mostly in the browser (Gmail, Google Docs, Notion web, LinkedIn, web forms), Grammarly Free covers most of your needs at no cost. Its browser extension provides real-time spelling and basic grammar correction everywhere you write in Chrome or Safari. If you need style coaching on top of that, Grammarly Premium becomes relevant.
If you write across multiple app types - native apps, web apps like Slack, and the browser - macOS autocorrect plus Grammarly still leaves gaps: autocorrect skips web apps like Slack, and Grammarly only suggests, so every fix waits for a click. Charm corrects as you type across all three.
For privacy requirements, macOS autocorrect and Charm both process text on-device. Grammarly sends your text to its servers for processing. For legal, medical, financial, or otherwise sensitive writing, on-device tools are the appropriate choice.
For maximum grammar detail on specific documents - cover letters, published essays, formal proposals - Grammarly Premium's style and tone analysis goes deeper than Charm's Polish feature. Many writers use both: Charm for real-time coverage across your Mac during the day, and Grammarly Free in the browser for a final review pass on important documents before they are sent.
The tools are not competitors in the same space - they have genuinely different coverage models. Understanding those differences makes it easy to choose what you actually need.
Frequently asked questions
Is Grammarly the same as autocorrect?
No. Autocorrect is a feature category that replaces misspelled words in real time. Grammarly is a specific product that includes autocorrect-style spelling correction plus grammar checking, style analysis, and tone detection. Grammarly is one product in the writing correction space; autocorrect describes a feature type that appears in many products including macOS and Charm.
Is Grammarly better than Mac autocorrect?
Grammarly is more capable in terms of grammar and style, and with its Mac app it reaches desktop apps as well as the browser, but every fix is a suggestion you accept. macOS autocorrect is built into native apps but offers no grammar checking. Which is "better" depends entirely on how you like to write.
Does Grammarly replace autocorrect on Mac?
Not fully. Grammarly adds suggestions in your browser and, through its Mac app, in desktop apps such as Apple Mail, Word and Slack, but it does not fix words as you type, so macOS autocorrect keeps running alongside it in native apps. They do not conflict. For corrections made as you type in more places, add a tool like Charm.
What is the difference between Grammarly and Charm?
How they correct is the primary difference. Grammarly suggests fixes for you to accept and offers detailed style analysis. Charm corrects as you type across your Mac, offering spelling, grammar, and word prediction. Charm is $19.99 once. Grammarly Premium is $144/year.
Should I use both autocorrect and Grammarly?
Using both is reasonable if you write heavily in both native Mac apps and the browser. They do not conflict. A practical alternative is Charm plus Grammarly Free: Charm correcting as you type, Grammarly Free in the browser for a final pass on important documents. That combination costs $19.99 total.