🧠 ALRA — Your Smart Chrome Companion
🚀 Inspiration
The frustration of modern web browsing inspired Alra. We’ve all been there — 50 tabs open, endless scrolling, intrusive ads, and losing track of what we were researching after switching devices. Browsing became a mental tax instead of a productivity tool.
When Google announced Gemini Nano for Chrome — an on-device AI model — we saw a once-in-a-decade opportunity. Why not make the browser intelligent without compromising privacy? No cloud calls, no lag, just a fast, private, on-device AI experience that helps users focus, summarise, and think better.
We wanted to build something that doesn’t just “add AI” to Chrome, but makes Chrome feel like it understands you.
💡 What it does
Alra transforms Chrome into a personal AI assistant built right inside your browser.
🧩 Smart Highlights: Automatically highlights the most relevant sections of any webpage in real-time.
🧠 AI Summaries: Generates concise, key-point summaries for long articles using Chrome’s PromptAPI.
🔒 Productivity Mode: Locks unrelated pages and keeps your focus sharp when you’re deep in work.
🔄 Cross-Device Sync: Predicts what tabs you’ll need next and syncs them across devices via Chrome Storage Sync.
🖼️ Image Insights: Click Analyse Image to instantly get context and visual details — using the PromptAPI when online, and a local fallback system when offline.
💬 Smart Nudges: Suggests actions intelligently based on your browsing behavior.
📊 Productivity Stats: Tracks your time, focus, and efficiency improvements.
Everything runs locally, built on top of Chrome’s AI infrastructure, ensuring zero data leaves your device.
🛠️ How we built it
Tech Stack:
TypeScript — for type safety and maintainability
Manifest V3 — latest Chrome standard
Chrome PromptAPI — for summarization, image insights, and text rewriting
Chrome Storage Sync — cross-device data sync
IndexedDB — local metric tracking
Webpack + TailwindCSS — lightweight, fast UI
Architecture:
We built a content script that injects a floating action button (FAB) into every page. An AI bridge script is injected directly into the page context to securely access window.ai. The background service worker handles tab prediction, sync, and offline fallback.
All AI processing happens locally or through the built-in PromptAPI — never external servers.
Mathematically, we can express Alra’s predictive behavior as:
P(T_{next}) = f(T_{prev}, C_{context}, U_{pattern})
where is the predicted tab, the previous tab, the content similarity, and the user’s historical browsing behavior.
🧩 Challenges we ran into
Immature Chrome AI APIs: Gemini Nano’s integration was under-documented and unstable. Solution: Built a custom message-passing bridge to safely interact with window.ai.
Massive Model Size: Gemini Nano required a 1.7GB download from chrome://components. Solution: Added clear user setup guidance and fallback systems for when Nano isn’t ready.
Content Security Policy (CSP) Restrictions: Chrome blocked dynamic imports and inline scripts. Solution: Consolidated everything into a single bundled script for flawless execution.
Mobile Limitations: Chrome mobile doesn’t support extensions. Solution: Leveraged Chrome’s Recent Tabs and Sync features to mimic seamless continuity.
Overhelpful AI Behavior: Early versions were intrusive with too many pop-ups. Solution: Switched to user-triggered FAB design — help when asked, never forced.
🏆 Accomplishments we’re proud of
✅ Truly Privacy-First AI — 100% on-device processing.
✅ Multimodal Features — Text + image understanding via PromptAPI.
✅ Performance Gains — Reduced reading time, fewer distractions, measurable productivity improvements.
✅ Elegant Integration — Single clean FAB interface.
✅ Cross-Device Continuity — Smart sync without any external database.
✅ Lean Build — 89.4 KB content script, <500ms load time.
📚 What we learned
Less is More: Simplicity wins. We removed redundant features and focused on doing a few things really well.
Privacy Builds Trust: Local-first architecture isn’t just good tech — it’s good ethics.
On-Device AI is the Future: Instant results, full control, no data risk.
UI Must Teach Itself: If a user needs documentation, the design failed.
Respect the Platform: Instead of fighting Chrome’s limitations, we used them to our advantage.
💭 Final Thought
Alra is more than an AI assistant — it’s a step toward a browser that thinks with you. Built with care, engineered within constraints, and designed for real people who want the web to feel human again.
Built With
- chromeextensionmanifestv3
- chromepromptapi
- chromestoragesyncapi
- gemininano
- indexeddb
- tailwindcss
- typescript
- webpack5
- writerapi
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