Currency Converter

Before 1971, the value of the US Dollar was fixed to the physical price of gold, and many global currencies were fixed to the US Dollar. Today, almost all major fiat currencies operate on a Floating Exchange Rate.

The value of a currency (like the Euro) is determined entirely by real-time supply and demand in the global Foreign Exchange (Forex) market. If international investors want to buy European stocks, they must first buy Euros, driving the price of the Euro up relative to their home currency.

Because currency rates change every second during market hours, it is impossible to hardcode them into an application. Instead, this tool performs an API Fetch.

1. The tool sends an HTTP request to a financial data provider.
2. The provider responds with a JSON payload containing the current exchange rates (usually pegged against a base currency like USD).
3. The tool uses simple cross-multiplication to convert your requested amount between any two currencies in the payload.

To respect API rate limits and to ensure the tool remains usable even if you lose your internet connection (e.g., while traveling internationally), the tool aggressively caches the API response in your browser's LocalStorage.

If the network request fails, the tool falls back to the last known good rates and explicitly displays the timestamp of when those rates were fetched, allowing you to estimate conversions while completely offline.