Harper
Harper: A private, free English grammar checker for writers, developers, and technical teams. Ranked #20 of 88 in Grammar Checkers by our editors (6.7/10); pricing: Free plan; best for privacy-focused English users and developers.
At a glance
- Editor score6.7 / 10
- PricingFree plan
- Best forPrivacy-focused English users and developers
- Free planYes
- Paid fromFree
- Facts checked20 Sep 2026
Where it wins
- Free, open-source checking with no account or credit card required
- Offline, on-device analysis for spelling, grammar, and punctuation
- Broad editor, browser, desktop, and developer integrations
Where it doesn't
- Coverage is centered on English and its dialects
- It does not include AI features
- Desktop text-field integration is specific to macOS
Our verdict on Harper
Harper is a free, open-source grammar checker for writers, developers, and technical teams. It checks spelling, capitalization, grammar, punctuation, and phrasing locally on the device. The product supports English dialect selection, including British, American, Canadian, Australian, and Indian English. Its privacy-focused design suits people who want offline analysis without creating an account, while its developer integrations make it relevant for technical writing and code-adjacent workflows.
Harper’s ecosystem spans Chrome and Firefox extensions, Microsoft Edge, VS Code, Cursor, Obsidian, WordPress, Neovim, Zed, Helix, Emacs, Sublime Text, and macOS apps. Developers can also work with its Language Server Protocol integration, JavaScript library, and Rust crate. User, workspace, and file-local dictionaries provide control over terminology, while custom grammar rules through Weir support specialized writing conventions. The platform coverage includes web, Windows, macOS, Linux, browser extensions, and an API, although system-wide macOS text-field integration is specific to macOS.
The published Free plan costs $0 USD and includes local grammar checking, open-source licensing under Apache-2.0, and no account or credit card requirement. There are no paid tiers described, so the product is straightforward to evaluate and adopt without a subscription decision. Harper is a strong choice for privacy-focused English users, developers, and technical teams that value local processing, customization, and editor support. It is less suitable for users seeking broad multilingual coverage, AI-based writing assistance, or mobile-focused checking.
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Harper pricing
All 1 Harper plans and prices →
Harper fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Free |
| Browser extension | Yes |
| Desktop app | Yes |
| Mobile app | Not verified |
| Style suggestions | Yes |
| Tone detection | Not verified |
| Languages supported | 1 |
| Deployment | Desktop, Browser extension |
| Platforms | Web, Windows, macOS, Linux, Chrome extension |
| Support | Community, Docs |
| Built for | Solo, Small business (editorial estimate) |
| Integrations | 15 integrations: Chrome, Microsoft Edge, Firefox, Visual Studio Code, Cursor, Obsidian … See all → |
| Pricing | Free plan (source) |
| Website | writewithharper.com |
| Facts checked | 20 Sep 2026 |
Harper integrations
Harper lists 15 integrations on its own site.
- Chrome
- Microsoft Edge
- Firefox
- Visual Studio Code
- Cursor
- Obsidian
- WordPress
- Neovim
- Zed
- Helix
- Emacs
- Sublime Text
- Language Server Protocol
- JavaScript library
- Rust crate
Alternatives to Harper
- GrammarlyA broad writing assistant with strong grammar, tone, rewriting, and AI coverage.9.4
- LanguageToolA broad multilingual checker with open-source and self-hosting options.9.2
- Microsoft EditorA strong Microsoft 365 writing assistant with focused platform coverage.9.0
Also Ranked In
Harper is ranked in 2 of our directories.
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Featured on iTechGuides
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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