GramVault

Chrome extension for real-time grammar checking powered by local or cloud LLMs.
Works like Grammarly but your text stays private — locked in your vault.

Screenshots

Badge panel — inline diff with one-click fix	Auto tone check — badge pill + score popup
Settings — provider, model, LLM frequency	Custom dictionary — add words to ignore

Features

• Two-tier checking: Instant rule-based checks (150ms) + LLM deep analysis (configurable)
• Floating badge: Grammarly-style error count badge on every text field — click to fix
• Diff view: Each error shows original struck through → suggested fix inline
• Severity levels: Critical / Warning / Suggestion — color-coded dots per issue
• Quick actions: Rewrite, Professional, Friendly, Concise, Elaborate, Summarize, Bullets, Tone Check — all from the badge panel
• Model switcher: Change model directly from the badge panel without opening settings
• Batch check: "Check page" scans all text fields on the current page at once
• Right-click menu: Select text and use GramVault context menu for any action
• Fix all: One-click to apply all grammar fixes at once
• Tone check: Detects tone with score bar and rewrite suggestions
• Custom dictionary: Add words to skip (technical terms, names, acronyms)
• Multi-language: English, Spanish, French, German, Portuguese, Italian, Dutch, Japanese, Chinese
• Writing stats: Daily check count, errors found, and fixes applied
• Keyboard shortcut: Ctrl+Shift+G (Mac: MacCtrl+Shift+G) opens the badge panel
• Multi-provider: Ollama, LM Studio, OpenAI, Anthropic, Gemini, OpenRouter
• Local first: Prioritizes local providers — text never leaves your device
• iframe support: Works in Gmail compose, Outlook web, and embedded editors
• Debug panel: Floating log panel for troubleshooting (toggle in settings)

Setup

1. Install the extension

1. Open chrome://extensions
2. Enable Developer mode (top right)
3. Click Load unpacked and select this folder

2. Set up a local LLM (recommended)

Ollama:

# Install from https://ollama.com
ollama pull gemma3:1b    # Fast, good for grammar
ollama serve

# Allow Chrome extension access
launchctl setenv OLLAMA_ORIGINS '*'
# Then restart Ollama

LM Studio:

1. Download from https://lmstudio.ai
2. Load any model
3. Enable the local server (localhost:1234)

3. Configure

Click the extension icon to open settings:

• Provider: Choose Ollama, LM Studio, or a cloud provider
• Language: Set your writing language (default: Auto-detect)
• Model: Auto-detected from your provider, small models recommended
• LLM Frequency: How often the LLM runs (on pause, on sentence end, manual, or disabled)
• API Key: Required for cloud providers only
• Custom Dictionary: Add words to ignore (technical terms, names, etc.)

Usage

Automatic checking

Type in any text field — rule-based errors appear instantly (red outline), LLM errors follow based on your frequency setting.

Badge panel

Click the floating badge (bottom-right of text fields) to:

• See all errors with diff view (original → fix) and severity dots
• Switch model without opening popup
• Run quick actions (Rewrite, Professional, Tone, etc.)
• Batch-check all fields on the page
• Fix all issues at once

Keyboard shortcut

Ctrl+Shift+G (Mac: MacCtrl+Shift+G) opens the badge panel for the focused field.

Right-click menu

Select text, right-click > GramVault for:

• Check Grammar (with auto-correct)
• Rewrite / Make Professional / Make Friendly / Make Concise
• Elaborate / Summarize / Convert to Bullets / Reformat
• Tone Check

Recommended models (by speed on Apple Silicon)

Model	Size	Notes
gemma3:1b	1B	Fastest, good for basic grammar
llama3.2:3b	3B	Solid balance
qwen3:1.7b	1.7B	Good small model
phi4-mini	3.8B	Strong reasoning
gemma3:4b	4B	Good quality
qwen3:8b	8B	Best quality under 8B

Rule-based checks (no LLM needed)

These run instantly with zero latency:

• Double words ("the the")
• A/an misuse ("a apple")
• Common misspellings (~200 words)
• Missing capitalization after periods
• Double spaces
• Missing space after punctuation
• Subject-verb agreement (simple cases)
• Unclosed quotes
• Common confusions (its/it's)
• Homophones (then/than)
• Gender-neutral language suggestions
• Run-on sentence detection

Files

manifest.json    — Chrome extension config (Manifest V3)
background.js    — Service worker: multi-provider API, context menus
content.js       — Content script: detection, badge, overlays, popups
content.css      — All visual styling
rules.js         — Fast rule-based grammar checker
popup.html/js/css — Settings UI
icons/           — Extension icons