Charm and LanguageTool both fix spelling and grammar, but they behave very differently on a Mac. LanguageTool supports over 25 languages; on Mac it works in browsers and, through its desktop app, in Apple Mail, Notes and Messages, with Word and Slack in beta. It checks your text in the cloud. Charm corrects as you type across your Mac, processes text on-device, and costs $19.99 once versus LanguageTool Premium's $60 per year.
What does each tool actually cover on Mac?
This is where the comparison is decided for most users.
LanguageTool on Mac comes in two parts. A browser extension covers Chrome, Firefox, Safari, and Edge. A Mac app checks text in Apple Mail, Notes and Messages, with Word, Slack and Teams in beta. In any other app, you bring text into LanguageTool's editor with a shortcut and copy it back. Every check needs an internet connection, and like Grammarly it shows suggestions for you to accept.
That limitation matters more than it sounds. The average Mac user spends a significant portion of their writing time outside the browser: in email clients, messaging apps, document editors, and developer tools. A grammar checker that only works in browser tabs is covering a fraction of daily writing.
Charm is a native macOS menu bar app that uses accessibility APIs to work in every text field on your Mac. Mail, Slack, Notes, VS Code, Obsidian, Pages - it does not matter which app you are in. Charm's three features - Spells (spelling correction), Polish (grammar), and Oracle (word prediction) - run invisibly in the background wherever you type. You configure it once. It covers everything.
How do prices compare between Charm and LanguageTool?
LanguageTool has a free tier, which genuinely exists and is usable for basic grammar checks. But the free version limits daily usage, shows upgrade prompts, and withholds premium grammar rules. For consistent, unlimited use, you need LanguageTool Premium at $60 per year.
Charm costs $19.99 once. No subscription, no renewal, no tiered features. One payment covers up to 3 Macs and includes updates. After one year, a LanguageTool Premium subscriber has spent three times more than a Charm user - and continues paying annually for every year that follows. Over three years, that gap reaches $180 versus $19.99.
For English-language Mac users who want system-wide coverage, the value equation strongly favours Charm.
| Feature | Charm | LanguageTool |
|---|---|---|
| Works across your Mac | Yes | Mail, Notes, Messages; others via its editor |
| On-device processing | Yes | No - cloud-based |
| Languages supported | English | 25+ languages |
| Word prediction | Yes - Oracle feature | No |
| Price | $19.99 once | $60/year (Premium) |
| Free tier | No | Yes (limited) |
Does LanguageTool protect your privacy on Mac?
LanguageTool's browser extension and desktop editor both route text through its cloud servers for analysis. Everything you type in a covered field is sent to LanguageTool's infrastructure to be processed. The company's privacy policy notes that data is handled under GDPR, but your text is still leaving your device and passing through a third-party server.
For most casual users, this is an acceptable trade-off. But for journalists, lawyers, medical professionals, or anyone writing commercially sensitive content, cloud-based text processing carries real risk. According to a 2023 survey by the Identity Theft Resource Center, 47% of professionals reported concerns about cloud productivity tools handling sensitive workplace communications.
Charm processes all corrections on-device using Apple's native text processing frameworks. Your keystrokes never leave your Mac. There is no account, no server connection, no data retention policy to read. For privacy-conscious users, this is not a minor feature - it is the deciding factor. The best LanguageTool alternatives for Mac that prioritise privacy all share this characteristic.
Where does LanguageTool genuinely win?
It is worth being direct about where LanguageTool is the better tool.
Multilingual support is LanguageTool's clearest strength. It checks grammar in over 25 languages, including German, French, Spanish, Portuguese, Dutch, Polish, and more. The quality of its non-English grammar rules is genuinely strong - particularly for German, which is its most mature language. If you write regularly in any language other than English, Charm cannot help you. LanguageTool can.
LanguageTool also provides style suggestions that go beyond grammar: passive voice detection, redundancy flags, readability hints, and formality scoring in its Premium tier. These are editorial tools, not just correctness checks. If you want feedback on how your writing reads - not just whether it is grammatically correct - LanguageTool's style layer adds value that Charm does not replicate.
The open-source core is another real advantage. Technical users can self-host LanguageTool's server locally, which eliminates the cloud privacy concern and provides offline access. It requires Java and manual configuration, but the option exists. If you want to compare options more broadly, see our roundup of the best LanguageTool alternatives for Mac.
Which tool is better for everyday Mac writing?
For the majority of English-speaking Mac users, Charm covers more ground where it counts. LanguageTool's Mac app covers a short list of apps, with others handled through its editor, and every check goes through its servers. Charm corrects as you type in the apps you use, on your Mac.
Charm's Oracle feature is also something LanguageTool has no equivalent for. Oracle predicts the next word as you type, surfacing completions in a subtle inline suggestion - similar to how predictive text works on iPhone, but running across your Mac and powered entirely on-device. For high-volume writers, this accelerates output in a way grammar checking alone does not.
If you are deciding between the two tools, ask one question first: do you write primarily in English, and want mistakes fixed as you type? If yes, Charm is the practical choice. If you write in multiple languages and are happy to review suggestions, LanguageTool's strengths become more relevant. You can also read how Charm compares to Grammarly for another angle on this category, or check our best autocorrect apps for Mac roundup for the full landscape.
What does setting each one up involve?
LanguageTool needs an account for Premium, and on Mac it is two installs: the browser extension, and the Mac app, which checks text in Apple Mail, Notes and Messages, with Word, Slack and Teams in beta. In other apps you bring text into its editor with a shortcut. Every check needs an internet connection unless you run your own LanguageTool server.
Charm is one download. On first launch it walks you through two macOS permissions (Accessibility and Input Monitoring), your licence key, turning off macOS autocorrect so the two do not both edit the same word, and choosing an engine: Fast (about 1.5 GB, for Macs with 8 GB of memory), Best Quality (about 2.3 GB, for 16 GB) or Built-In Spellcheck with no download. After that there is no account to create and nothing to set per app; code editors start in Manual, where you select text and press Option-Command-V.
Frequently asked questions
Does LanguageTool work in every Mac app?
Not every one. LanguageTool's Mac app works in Apple Mail, Notes and Messages, with Word, Slack and Teams in beta; other apps go through its editor with a shortcut. It needs an internet connection for its checks. For correction as you type across your Mac, on-device, you need a tool like Charm. See the complete guide to autocorrect on Mac for a full breakdown of how different tools integrate with macOS.
Is Charm or LanguageTool better for non-English writers?
LanguageTool is the stronger choice for non-English writers. It supports over 25 languages with genuinely strong grammar rules, particularly for German and French. Charm currently supports English only. If you write primarily in a language other than English, LanguageTool's multilingual coverage is a clear advantage that Charm cannot match.
Which is cheaper - Charm or LanguageTool?
Charm is significantly cheaper for English users. Charm costs $19.99 as a one-time purchase with no subscription. LanguageTool Premium costs $60 per year. Over three years, LanguageTool costs $180 compared to Charm's single $19.99 payment. LanguageTool offers a free tier, but it limits daily checks and withholds advanced grammar rules.
Does LanguageTool work offline on Mac?
No, not in its standard form. LanguageTool's browser extension and desktop editor both send text to cloud servers, which requires an active internet connection. A self-hosted open-source version exists for technical users but requires Java and manual setup. Charm processes everything on-device and works fully offline without any configuration.
What does Charm have that LanguageTool doesn't?
Three things: system-wide coverage across your Mac (not just browsers), fully on-device processing so your text never leaves your Mac, and Oracle - a word prediction feature that suggests completions as you type. LanguageTool has no equivalent to any of these on Mac. For users who write in English across native Mac apps, these gaps are substantial.