TwinPen

AI writing assistant. Improve spelling, grammar, and flow anywhere you write. Create custom styles to match your voice.

TwinPen AI Writing Assistant Transform Your Writing, Instantly TwinPen is your intelligent writing companion that works seamlessly wherever you write online. Powered by cutting-edge AI models, TwinPen helps you craft perfect text with your unique voice—whether you're composing emails, writing social media posts, drafting documents, or filling out forms. Write better. Write faster. Write with confidence. Why TwinPen? Works Everywhere: TwinPen intelligently detects text fields across the web. No matter where you write—Gmail, LinkedIn, X, Telegram, WhatsApp, or any website—TwinPen is there to help. Your Style, Your Voice: Create unlimited custom writing styles that match your unique voice. Whether you need professional business communication, friendly casual tone, or formal academic writing, TwinPen adapts to you. Complete Privacy: Your data stays yours. TwinPen uses your own OpenAI API key, stored securely on your device. No data is sent to third-party servers except OpenAI (using your credentials). Key Features Inline Text Improvement The smartest way to improve your writing. TwinPen automatically detects when you're typing in any text field and displays a floating icon. One click instantly improves your entire text—no popups, no interruptions. It's like having a writing assistant watching over your shoulder, ready to help the moment you need it. Right-Click Context Menu Select any text on any webpage, right-click, and choose "Improve writing" to get AI-powered suggestions. Perfect for refining existing content, improving selected passages, or polishing text you've already written. Keyboard Shortcut Press Ctrl+# (or Cmd+# on Mac) while typing in any text field for instant improvement. Power users love this lightning-fast workflow. Customizable Writing Styles Create unlimited custom writing styles with your own descriptions. Need a style for "customer support emails"? Create it. Want "academic paper tone"? Define it. TwinPen comes with four pre-installed styles (Professional, Formal, Friendly, Concise) that you can edit or use as-is. Every style is fully customizable—change names, descriptions, and create new ones to match your exact needs. Latest AI Models Choose from the fastest and most advanced AI models available: GPT-5.1: Latest and most powerful GPT-5: High-performance option GPT-5 Mini: Balanced speed and quality GPT-5 Nano: Ultra-fast for quick improvements Per-Site Control Enable or disable the floating icon on specific websites. Love the icon on Gmail but find it distracting on Twitter? Toggle it per domain with one click. Review Before Applying See the improved text before applying it. Generate multiple variations, compare suggestions, and choose the perfect version. Copy to clipboard or apply directly—you're in complete control. How It Works Step 1: Setup (One-Time) 1. Install TwinPen from the Chrome Web Store 2. Right-click the extension icon and select "Options" 3. Enter your OpenAI API key (get one at platform.openai.com/api-keys) 4. Choose your preferred AI model 5. Select or create your default writing style Step 2: Start Writing Better Method 1 - Inline Icon (Easiest): Click into any text field See the floating icon appear Click it to instantly improve your text Done! Your text is improved in-place Method 2 - Right-Click: Select any text on a webpage Right-click and choose "Improve writing" Review the suggestion in the popup Apply, generate a new version, or copy to clipboard Method 3 - Keyboard Shortcut: Type in any text field Press Ctrl+Shift+I (Mac: Cmd+Shift+I) Text is improved instantly Perfect For Professionals: Write polished emails, reports, and communications that make the right impression. Professional and formal styles help you maintain the perfect tone for business contexts. Content Creators: Refine social media posts, blog articles, and marketing copy. Create custom styles for different platforms and audiences. Students: Improve academic writing, essays, and assignments. Use formal or concise styles to meet academic standards. Non-Native Speakers: Get instant help with grammar, spelling, and natural phrasing. TwinPen helps you write like a native speaker. Anyone Who Writes Online: Whether you're filling out forms, writing comments, or composing messages, TwinPen makes every word count. Privacy & Security Your Data, Your Control Your OpenAI API key is stored locally in Chrome's secure sync storage All API calls use your credentials directly—no intermediate servers Writing history is stored locally on your device (optional, can be disabled) No data is sent to third-party servers except OpenAI (using your API key) Future cloud features will be opt-in with explicit consent Transparent & Trustworthy Open architecture you can inspect No hidden data collection No tracking or analytics Complete control over your data Advanced Features Writing Style Management Edit Default Styles: Modify the pre-installed Professional, Formal, Friendly, and Concise styles to match your preferences Create Custom Styles: Build unlimited custom styles with descriptions up to 200 characters Set Default Style: Choose which style is used automatically for inline improvements Style Library: Manage all your styles from the options page Smart Detection TwinPen intelligently detects: Standard input fields and textareas Contenteditable divs (like Gmail compose, LinkedIn posts) Special editors (WhatsApp Web, Facebook Messenger) Rich text editors and WYSIWYG editors Visual Feedback Loading State: Icon shows spinner while processing Success State: Checkmark confirms improvement applied Error State: Clear error messages if something goes wrong Smooth Animations: Polished UI that feels native Use Cases Email Composition Write professional emails that get responses. TwinPen helps you craft clear, concise, and appropriately toned messages for any recipient. Social Media Create engaging posts that resonate. Use friendly or concise styles to match your platform's tone, or create custom styles for different audiences. Document Writing Improve reports, proposals, and documents. Professional and formal styles help you maintain the right tone for business contexts. Form Filling Make every form submission count. TwinPen helps you write clear, professional responses that make the right impression. Academic Writing Refine essays and assignments. Use formal styles to meet academic standards while maintaining your unique voice. Customer Support Craft helpful, professional responses. Create custom styles for different types of customer interactions. Getting Started 1. Install TwinPen from the Chrome Web Store 2. Configure your OpenAI API key in the options page 3. Choose your preferred AI model and writing style 4. Start writing better text instantly! Need Help? Visit twinpen.com for documentation and support Check the options page for detailed settings All features are intuitive and easy to use