promptLY

While others send your writing to the cloud, promptLY processes everything locally with Gemini Nano. Professional AI writing assistance that's instant, private, and works offline. No compromises.

Comment

Inspiration

Every time I used online AI tools, I wasted minutes switching tabs, pasting text, and risking my privacy. I called it the three-minute tax of modern AI use.
I wanted to remove that friction — to bring powerful, private AI writing directly into Chrome, where work already happens. That’s how promptLY began.

What it does

promptLY refines text instantly inside Chrome’s side panel using the new LanguageModel API powered by Gemini Nano.
Highlight any text, right-click → promptLY → Refine.
It can simplify, humanize, elaborate, or auto-reply to emails — all completely offline and 100 % private, with zero data leaving your device.

How I built it

  • Built with Chrome Extension SDK + built-in AI (window.ai / LanguageModel APIs)
  • Added context-menu + side-panel integration for smooth UX
  • Implemented dual-API fallback for cross-version compatibility
  • Designed Smart History, Inline Feedback, and Format Preservation features
  • Runs entirely on-device with Gemini Nano (~2 GB local model)
  • Open-sourced under MIT License → GitHub

Challenges I ran into

Enabling Chrome’s experimental Gemini Nano flags, testing local model downloads, and making the UI feel native to Chrome were tough.
Balancing performance and privacy while keeping instant response times required careful tuning and debugging.

Accomplishments I’m proud of

  • First working AI refinement tool built entirely on Chrome’s on-device Gemini Nano
  • Full offline capability — no servers, no subscriptions
  • Polished, distraction-free UX with real-time feedback
  • Completed a working prototype, full documentation, and demo video within the hackathon timeframe
  • Published on the Chrome Web Store and continue scaling the ecosystem

What I learned

Integrating Chrome’s on-device AI proved that local AI is the future.
I learned to optimize user flows for privacy-first experiences and to communicate transparency through clean, open-source design.

What’s next for promptLY

  • Add new Quick Prompts (“Fix Grammar”, “Make Concise”, “Add Humour”)
  • Add multi-language support (French, German, Hindi, Portuguese)
  • Integrate with Gmail and Google Docs
  • Launch a community Prompt Marketplace

Built With

  • chrome-extension-sdk
  • chrome-languagemodel-api
  • css3
  • gemini-nano
  • github
  • html5
  • javascript-(es6)
  • local-storage-api
  • manifest-v3
  • mit
  • window.ai-api
Share this project:

Updates