Wandpen is a Chrome extension that provides AI-powered writing assistance. It helps users improve writing, fix grammar, rewrite content, translate text, brainstorm ideas, and chat with web pages. Key features include: working on any website, page chat for summarization and content creation, custom prompts organized by folders, free unlimited writing powered by Gemini Nano (offline and private), voice-to-text transcription, and the ability to bring your own API keys (BYOK) for access to models from OpenAI, Anthropic, Google, and others. The extension is accessible via keyboard shortcuts (Option+W on Mac, Alt+W on Windows/Linux). Plans include a free tier with limited cloud generations, a Pro subscription for unlimited cloud access, and a lifetime BYOK option.