Know the air you're breathing.
Project brief
Moved live air-quality context into the browser toolbar and current page without accounts, analytics, or remote key storage.
Hiring signal
Senior ownership across product framing, execution scope, and shipped interface quality.
Engineering read
Focus on constraints, architecture bets, external systems, and data-flow decisions.
A free, open-source Chrome extension that keeps live air quality data one click away, built for Indian cities on top of OpenAQ and Rainmatter's own OAQ platform.
Air quality data that matters for day-to-day decisions — should I run outside today — is scattered across dashboards nobody checks. It needed to live somewhere people already look: the browser toolbar.
I built it privacy-first from the frontend up: the API key never leaves the user's device, there's no tracking or analytics, and the extension still shows the last good reading when offline instead of failing silently.
Project method
The extension had to keep air-quality data close to where people already spend time: the browser toolbar and current page. Requirements included a popup dashboard, settings page, background refresh, optional overlay, CPCB AQI categories for India, configurable providers, and a privacy model where API keys stay on-device.
A Manifest V3 Chrome extension with vanilla JavaScript was chosen to avoid a runtime build dependency and keep the package self-contained. The background service worker handles scheduled fetch and cache, the popup reads the latest snapshot, the options page validates API configuration, and the content script displays the overlay.
The design system was deliberately compact and utility-focused: a small popup, direct pollutant breakdown, clear AQI category language, masked settings values, and minimal overlay chrome. That suited a browser extension better than a heavier app-style interface.
The MVP was the full private loop: save settings locally, fetch OpenAQ or OAQ data, normalize measurements, derive indicative AQI when needed, cache the last good snapshot, and render the result in both popup and overlay. Analytics, accounts, and remote sync were intentionally excluded.
Development started with the air-quality normalization library and CPCB breakpoint tests, then expanded into settings validation, background alarms, popup rendering, and overlay behavior. Browser smoke tests were added to verify the MV3 service worker, local-only credential storage, masked settings, and packaged extension output.
Conclusion
A toolbar popup with a live AQI gauge and pollutant breakdown (PM2.5, PM10, NO₂, SO₂, CO, O₃), CPCB AQI categories for Indian cities, dual API support so it works with OpenAQ or OAQ, and an optional on-page overlay badge for at-a-glance readings anywhere on the web.
Proof list
Open channel
Architecture, AI workflows, design systems, and interfaces that need to hold up after launch.