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Browser Extension

Currency Converter

Whether you are shopping on international sites, planning a trip or managing global investments, get instant, accurate conversions you can trust.

GitHub
tcmhack.com/currency-converter
Currency Converter preview

Overview

A financial utility for travelers and shoppers that combines a live-update engine with local caching, so it keeps working without a connection.

Key features

  • Supports 99% of UN-recognized currencies and territories.

  • Daily-updated mid-market rates.

  • Full offline mode using the last cached rates.

  • PrivateConversions happen locally.

Challenges

  1. 01

    Caching rates every 24 hours for accurate offline math.

  2. 02

    High-precision arithmetic up to 6 decimal places.

  3. 03

    Codes, symbols and flags for 150+ countries in a small bundle.

  4. 04

    Graceful failover when the rates API is down.

Objectives

  1. 01

    Support virtually every global currency.

  2. 02

    Reliable daily mid-market rates.

  3. 03

    Local-first architecture for offline use.

  4. 04

    Results in under two seconds.

Outcome

  • Works in airports and low-connectivity zones.

  • Covers 99% of the world’s territories.

  • Compare international prices without leaving the tab.

  • Clean, ad-free and private.

Screenshots