Grammar checking that respects your privacy.
TextWarden checks your spelling and grammar while you type - in any app on your Mac. Unlike other tools, everything runs locally on your computer. Your writing never leaves your device.
Note
Beta Software: TextWarden is in active development and you may encounter bugs. For example, some visual underlines might be misaligned, some suggestions might not be perfect, or certain applications may not work as expected. Much like printers and projectors that still mysteriously fail on first try after decades of existence, macOS Accessibility APIs and the apps that implement them each have their own quirks that require app-specific tuning. That said, it should be stable enough for daily use and I'd love for you to try it! Your bug reports help make TextWarden better for everyone. Found something broken? Report it here.
Private by Design Your text stays on your Mac. No cloud servers, no accounts, no data collection. Works completely offline.
Blazingly Fast Powered by Harper, a high-performance Rust-based grammar engine.
Works Everywhere Integrates with most macOS apps through the Accessibility API - Mail, Outlook, Teams, Slack, and more.
Simple and Unobtrusive A small indicator and/or underline appears when issues are found. Click to see suggestions. Accept with one click. That's it.
- Real-time grammar and spelling - Catches errors as you type
- AI-powered style suggestions - Apple Intelligence (Foundation Models) for clarity and readability improvements (macOS 26+)
- AI Compose - Generate text from instructions using on-device AI (macOS 26+, Apple Silicon)
- Readability Score - Real-time Flesch Reading Ease score for text with 30+ words
- Multilingual awareness - Detects non-English documents and sentences, skipping grammar checks (no false positives on foreign text)
- Custom dictionary - Add your own technical terms and proper nouns
- Dialect support - American, British, Canadian, or Australian English
- App controls - Enable, disable, or pause checking per application
- Automatic updates - Stay current with optional update checks
- macOS 26 (Tahoe) or later
- Any Mac that supports macOS 26 (Intel or Apple Silicon)
Note for Intel Mac users: TextWarden runs on Intel Macs, but AI-powered style suggestions are not available. Apple Intelligence requires Apple Silicon (M1 or later) due to the Neural Engine hardware. Grammar and spelling checking work fully on Intel Macs.
- Download the latest release from the Releases page
- The DMG is a Universal binary that works on both Intel and Apple Silicon Macs
- Move TextWarden to your Applications folder and open it
- Grant Accessibility permission when prompted (required to read text in other apps)
- Recommended: Disable built-in spell/grammar checking in apps you use with TextWarden to avoid confusion from overlapping underlines (e.g., in System Settings → Keyboard → Text Input, or within individual apps like Slack, Word, etc.)
- Start typing - TextWarden works automatically in the background
For detailed explanations of all settings and how they affect your experience, see the Configuration Guide.
TextWarden continuously monitors your writing and highlights errors as you type. Corrections appear in a popover with one-click apply. Supported error categories include:
- Spelling mistakes and typos
- Grammar errors (subject-verb agreement, tense, etc.)
- Punctuation issues
- Capitalization errors
- Word choice and commonly confused words
- Redundant phrases
You can enable or disable specific categories in Settings.
Beyond rule-based grammar checking, TextWarden offers intelligent style suggestions powered by Apple Intelligence running entirely on your Mac. This feature is disabled by default and can be enabled in Settings → Style.
When enabled, style checking runs automatically after grammar analysis with smart rate limiting. You can also trigger it manually:
- Keyboard shortcut: Press
Option+Control+S(customizable) to run a style check on demand - Indicator click: Click or hover over the style section of the capsule indicator
When using the keyboard shortcut with text selected, only the selected portion is analyzed. Without a selection, the entire text field is analyzed.
Available writing styles: Default, Concise, Formal, Casual, and Business.
AI Compose lets you generate text directly from natural language instructions. Click the pen icon on the indicator (when style checking is enabled) to open the compose panel.
Use cases:
- Draft emails, messages, or responses
- Expand bullet points into full paragraphs
- Rewrite or rephrase selected text
- Generate placeholder content
Enter your instruction (e.g., "Write a polite decline for a meeting invitation"), choose a writing style, and press Enter. The generated text can be inserted directly or copied to clipboard. Use "Retry" to get alternative versions.
Like style suggestions, AI Compose runs entirely on-device using Apple Intelligence - your instructions and generated text never leave your Mac.
TextWarden uses document-level and sentence-level language detection to avoid false positives when you write in other languages. If more than 60% of a document is detected as German, Spanish, or another non-English language, all grammar checking is skipped for that document. For mixed-language documents, each sentence is analyzed independently - foreign-language sentences have their errors suppressed while English sentences are still checked. This handles both fully foreign documents and emails that include phrases like "Freundliche Grüsse" or "Merci beaucoup".
Supported languages for detection: Spanish, French, German, Italian, Portuguese, Dutch, Russian, Chinese, Japanese, Korean, Arabic, Hindi, Turkish, Swedish, and Vietnamese.
Control exactly where TextWarden runs:
- Enable or disable checking for specific applications
- Pause checking temporarily (1 hour, 24 hours, or indefinitely)
- Disable checking for specific websites when using browsers
- Custom dictionary - Add technical terms, proper nouns, or specialized vocabulary
- Dialect support - American, British, Canadian, or Australian English spelling rules
- Internet abbreviations - Recognizes "btw", "afaik", "imo" without flagging them
- IT terminology - Built-in dictionary of 10,000+ technical terms and company names
- Brand names - 2,400+ company/brand names (Fortune 500, Forbes 2000, global brands)
- Person names - 100,000+ international first names (US SSA + worldwide sources)
- Surnames - 150,000+ last names from US Census data
- Usage statistics - Track errors found and corrections applied (stored locally)
- Keyboard shortcuts - Customizable shortcuts for common actions
- Menu bar integration - Quick access to pause, resume, and settings
- Launch at login - Optionally start TextWarden when you log in
TextWarden can automatically check for updates and notify you when a new version is available. Enable automatic update checks in Settings → Advanced.
To receive early access to new features, enable the experimental channel in Settings. This includes alpha, beta, and release candidate versions.
TextWarden is a privacy-focused, local-first tool with certain trade-offs:
- macOS only - Available for Intel and Apple Silicon Macs running macOS 26+. There are no plans to support Windows or Linux - approximately 98% of TextWarden's development effort goes into macOS-specific integration: precise cursor positioning via the Accessibility API, pixel-perfect error underline placement, seamless text replacement that preserves formatting, and per-application behavior tuning. These deep OS integrations don't translate to other platforms.
- Style suggestions require Apple Silicon - AI-powered style suggestions use Apple Intelligence, which requires the Neural Engine in M1 chips or later. Intel Macs can use all grammar and spelling features but won't have access to style suggestions.
- English only - Grammar checking limited to English (Harper's current language support)
- Accessibility API constraints - Some apps with custom text rendering may not work correctly
- Text formatting - When applying corrections in some apps, formatting (bold, italic) may not be preserved
- Visual underlines - Not all applications support visual error underlines; see Tested Applications for details and the Troubleshooting Guide for help
If you need cross-platform support (Windows, Linux, iOS, Android), grammar checking in languages other than English, consider:
- Grammarly - Excellent product with broad application support and a refined user experience developed over many years
- LanguageTool - "Open-source" grammar checker with support for 30+ languages, available as browser extensions and desktop apps
TextWarden focuses specifically on privacy, local processing, and full transparency as an open-source project - which comes with the trade-offs mentioned above.
TextWarden never sends your text anywhere. All grammar checking and style analysis happens on-device using Harper (grammar) and Apple Intelligence (style suggestions). Block TextWarden in your firewall and it works exactly the same (except for automatic update checks).
The majority of TextWarden's code was generated using Anthropic's Claude, with human oversight, review, and testing throughout the development process.
The TextWarden logo was created with Recraft - an amazing AI image generation tool with background removal, image vectorization, and more. Highly recommended for creating app icons and design assets.
TextWarden is powered by Harper, an open-source grammar checker built in Rust by Automattic. Harper is what makes TextWarden fast and private - it runs entirely on your device without sending text to any server.
If you need grammar checking inside your browser with full support for rich text editors, form fields, and web apps, check out Harper's Chrome Extension. Unlike TextWarden (which uses macOS Accessibility APIs from outside the browser), Harper's extension runs directly in the browser with full DOM and JavaScript access - this means better integration with complex web applications like Google Docs, Gmail compose, and other rich text editors.
- Harper Website: writewithharper.com
- Harper Source Code: github.com/Automattic/harper
I used VoiceInk extensively while developing TextWarden. It saved me countless hours by letting me dictate AI prompts, documentation, and commit messages instead of typing everything. Like TextWarden, it runs entirely locally on your Mac. (Referral link - helps support TextWarden's development)
- swift-bridge - Rust/Swift interoperability
- whichlang - Language detection
- KeyboardShortcuts - Global keyboard shortcuts for macOS
- LaunchAtLogin-Modern - Launch at login functionality
- ConfettiSwiftUI - Confetti animations
TextWarden is a side project built during evenings and weekends. If you find it useful, you can support its development:
Tip: If you have an open issue or feature request, include the GitHub link in your message - supporters' requests get prioritized!
See the Troubleshooting Guide for help with common problems and how to collect diagnostic information.
TextWarden uses the macOS Accessibility API and works with most applications. Visual underlines (showing errors directly in the text) have been specifically tested and calibrated for:
| Application | Grammar Checking | Visual Underlines |
|---|---|---|
| Slack | Full | Full |
| Claude | Full | Full |
| ChatGPT | Full | Full |
| Perplexity | Full | Full |
| Safari | Full | Full |
| Chrome, Comet | Full | Full |
| Apple Mail | Full | Full |
| Apple Notes | Full | Full |
| Apple Messages | Full | Full |
| Apple Calendar | Full | Full |
| Apple Pages | Full | Full |
| Apple Reminders | Full | Full |
| TextEdit | Full | Full |
| Notion | Full | Partial** |
| Telegram | Full | Full |
| Full | Full | |
| Webex | Full | Full |
| Microsoft Word | Full | Full |
| Microsoft PowerPoint | Notes only* | Notes only* |
| Microsoft Outlook | Full | Full |
| Microsoft Excel | Not supported | N/A |
| Microsoft Teams | Full | Full |
| Proton Mail | Full | Full |
*PowerPoint exposes only the Notes section via the macOS Accessibility API. Slide text boxes are not accessible programmatically (Microsoft limitation), so grammar checking and visual underlines are limited to speaker notes. See PowerPoint documentation for details.
**Notion: Underlines appear for ~50% of text blocks. Due to Notion's React/Electron virtualization, some blocks aren't exposed in the accessibility tree. Errors in virtualized blocks show in the indicator count but without underlines. Shift+Enter (soft breaks) work; Enter (new blocks) may not. See Notion documentation for details.
Note
Terminal apps are not supported as their accessibility APIs typically don't expose text content in a way that's useful for grammar checking.
Other applications: TextWarden works with most apps that support standard text editing. Grammar checking and the floating error indicator work broadly; visual underlines may vary. Request support for additional apps.
- Bug reports: Open an issue with diagnostic information
- Feature requests: Use GitHub Discussions
- Questions: Check existing discussions or start a new one
If best-effort community support isn't sufficient for you and you need more advanced support, contact sales@textwarden.io.
Apache License 2.0
