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Currio — A silent Chrome extension that auto-converts every currency on any webpage into your own, the moment the page loads.

(Background: I built this so I wouldn't have to mentally convert foreign prices to CNY, and other things.)

How It Works

You visit amazon.com → $1,299 → ¥9,429

No clicks, no copy-paste, no new tab. The conversion sits right beside the original price, barely noticeable until you need it.

Features

• Auto-Detect — Recognizes $100, ¥1000, €50, £30, ₩50000, USD 100, 100 USD, NT$690, HK$100, and more
• Smart Inferrence — $ maps to 6+ currencies. Currio resolves it from page locale, browser language, TLD, and explicit currency codes
• Always Fresh — 45-min TTL rate cache, exponential backoff on failures, stale cache fallback
• React-Proof — Renders conversions via CSS ::after pseudo-elements (no DOM mutation), so SPAs don't break
• Zero Config — Detects your preferred currency from browser language on first install
• Site Blacklist — One-click to disable on specific domains
• Privacy First — No tracking, no data collection, rate requests go directly to ExchangeRate-API
• Lightweight — ~50KB unpacked, < 3% page overhead, < 10MB memory

Installation

Chrome Web Store

(Coming soon)

Manual (Developer Mode)

git clone https://github.com/gaojice/currio.git

1. Open chrome://extensions
2. Enable Developer mode (top right)
3. Click Load unpacked → select the currio folder

Architecture

content.js (DOM scanner)
  ├── TreeWalker + MutationObserver
  ├── Multi-pattern regex matching
  ├── Locale-aware source inference
  └── CSS data-attribute rendering

background.js (Service Worker)
  ├── Exchange rate fetching
  ├── 45-min cache
  └── Message routing (settings + rates)

popup.js (Browser Action)
  ├── Currency picker
  └── Site blacklist manager

Supported Currencies

Symbol	Resolves To
$	USD · CAD · AUD · HKD · SGD · TWD
¥ / ￥ / 元	JPY · CNY
€	EUR
£	GBP
₩	KRW
Multi-char	NT$ · HK$ · AU$ · CA$ · S$ · US$
Codes	USD · EUR · GBP · JPY · CNY · TWD · KRW · AUD · CAD · HKD · SGD

Privacy

Currio reads zero personal data. The only outbound request is to api.exchangerate-api.com for exchange rates. No browsing history, no analytics, no telemetry.

Roadmap

• Chrome Web Store publication
• Cryptocurrency support (BTC, ETH via CoinGecko)
• Optional IP-based geolocation for default currency
• Historical rate chart on hover

License

MIT

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_{Built with vanilla JS · Manifest V3 · exchange rates from ExchangeRate-API}

Support

If you find Currio useful, consider buying me a coffee ☕