How does WindowSill compare to Grammarly?

Grammarly is a dedicated writing assistant focused on grammar, tone, and style with real-time inline suggestions. WindowSill is a productivity command bar that includes AI writing features alongside media control, clipboard history, meeting management, and more. WindowSill supports 35+ languages, BYOK API keys, and local LLMs, while Grammarly is primarily English-focused with its own proprietary AI.

Is WindowSill cheaper than Grammarly?

Yes. WindowSill+ starts at $4/month and includes AI writing plus all productivity features. Grammarly Pro costs $12/month. WindowSill also offers a $48 lifetime option, while Grammarly is subscription-only. WindowSill's free tier includes full productivity features (no AI), while Grammarly's free tier offers basic grammar checking and 100 AI prompts per month.

Can WindowSill replace Grammarly?

For most users, yes. WindowSill's AI handles grammar correction, tone adjustment, translation, summarization, and custom prompts. However, Grammarly excels at real-time inline suggestions as you type and offers deeper English-language style analysis. If you primarily need grammar checking while typing, Grammarly is more specialized. If you want AI writing as part of a broader productivity toolkit, WindowSill is the better value.

WindowSill vs Grammarly | AI Writing for Windows Compared

Summary

Grammarly is a comprehensive writing assistant that works across web browsers, desktop applications, and mobile devices. It offers real-time grammar and spelling correction, tone detection, plagiarism checking, and sentence rewrites. Grammarly uses a freemium model with Pro features available through subscription at $12/month. It is primarily focused on English-language writing.

WindowSill is a Windows desktop command bar that provides AI-powered text assistance (grammar fix, rewriting, translation in 35+ languages, custom prompts) alongside productivity features like media control, clipboard history, meeting management, reminders, and image utilities. WindowSill supports BYOK models like OpenAI or local LLMs. It has a free-tier. Premium features are available via a $4/month subscription or a $48 lifetime license.

Feature comparison

	WindowSill	Grammarly
Grammar & Spelling	AI-powered proofreading via text selection with instant text replacement	Real-time inline suggestions as you type with detailed explanations
Tone Adjustment	Professional, casual, attention-grabbing, and custom tones presets	Advanced tone detection and suggestions for different contexts
Text Rewriting	AI-powered rewriting with one click and model selection	AI-powered rewriting with one click
Translation	35+ languages with instant translation	Not available
Custom AI Prompts	Create reusable prompts locally with variables (date/time injection and more)	Uses Grammarly's built-in prompts (100 free, 2,000 Pro)
Per-Prompt Model Selection	Choose different AI models per prompt	Proprietary AI only
Summarization	One-click summarize	One-click summarize
Plagiarism Detection	Not available	Built-in plagiarism and AI text detection (Pro)
AI Providers	8 built-in BYOK providers, local LLMs, and any OpenAI-compatible API	Proprietary AI only
Media Control	Built-in — Spotify, YouTube, Netflix, Apple Music, and more	Not available
Clipboard History	With screenshot protection and password hiding	Not available
Meeting Control	Mute, unmute, leave Teams meetings	Not available
Short-Term Reminders	Full-screen (ADHD-friendly) and toast notifications	Not available
Image & Video Utilities	Batch convert, resize, compress	Not available
Extensions	SDK with growing marketplace	Browser extension ecosystem
Enterprise & Organization	AI provider allow-lists, managed prompts, usage analytics	Custom roles & permission, usage analytics

Platform & Compatibility

WindowSill

OS: Windows 10 and 11
Memory: 300 MB recommended
Works in: Any application
Distribution: Microsoft Store + standalone installer (Pro)

Grammarly

OS: Windows, macOS, iOS, Android, Web
Memory: 8 GB recommended for optimal performance
Works in: Any application
Distribution: Direct download, browser stores, app stores

Pricing comparison

	WindowSill	Grammarly
Free Plan	All core productivity features (media, clipboard, reminders, utilities, extensions); no AI	Basic grammar & spelling; 100 AI prompts/month
Individual Paid	From $4/month or $48/year (WindowSill+)	$12/month (Pro)
One-Time License	$48 lifetime (BYOK only)	Not available
Enterprise	From $3.60/user/month with graduated discounts	Custom pricing (contact sales)
AI Prompts	Unlimited on any paid tier	2,000/month (Pro); unlimited (Enterprise)
Free Trial	1-week free trial	1-week free trial

Strengths & Gaps

WindowSill Strengths

AI writing as part of a full productivity toolkit
Translation into 35+ languages
BYOK with 8 built-in providers, OpenAI-compatible providers, and local LLMs
Use different models for different tasks
Custom reusable prompts with variable injection
Media control, clipboard, reminders built in
Privacy-first (local LLMs, screen recording protection)
Lifetime purchase option ($48)
Lower price than Grammarly ($4/mo vs $12/mo)
Enterprise AI governance (provider allow-lists, usage stats)

WindowSill Gaps

No real-time inline suggestions as you type
No plagiarism or AI text detection
Windows only (including browsers, but no mobile or macOS)
No detailed grammar explanations (doable through custom prompt)
No brand style guide or tone consistency features (doable through custom prompt)

Grammarly Strengths

Best-in-class real-time inline grammar suggestions
Detailed grammar and style explanations
Cross-platform (Windows, macOS, iOS, Android, web)
Plagiarism and AI text detection (Pro)
Brand style guide and tone consistency (Enterprise)
Trusted by 40M+ users and 50,000 organizations

Grammarly Gaps

Subscription only — no lifetime purchase
Primarily English-focused (limited multilingual support)
No BYOK or local LLM support — proprietary AI only
No custom prompt creation with variables
No productivity features beyond writing (no media, clipboard, meetings)
AI prompts capped at 2,000/month on Pro

Which to Choose?

Choose WindowSill if…

You want AI writing as part of a broader productivity toolkit.
You work in multiple languages, not just English.
You want to choose your own AI provider or use local LLMs.
You need custom reusable prompts for repetitive tasks.
You prefer a one-time $48 lifetime purchase over subscriptions.
You care about data privacy (local LLM, screen recording protection).
You want unlimited AI usage without prompt caps.

Choose Grammarly if…

You need real-time inline grammar suggestions as you type.
You write primarily in English and need deep style analysis.
You use macOS, iOS, or Android in addition to Windows.
You need plagiarism and AI text detection.
You want brand style guides and tone consistency for your team.
You prefer a simple, single-purpose writing tool.
You need detailed grammar explanations to improve your writing.

WindowSill vs Grammarly