forex_currency_conversion_historical #

A Dart package to fetch FREE foreign exchange (forex) rates, both historical and current.

Features #

• Completely free — No API keys required
• Historical rates — Rates dating back to January 1999
• Wide currency support — 150+ currencies via multiple data sources
• Safe numbers — Uses decimal package to safeguard against floating-point errors
• Automatic fallback — Leverages multiple data sources in case one fails for any reason

Data Sources #

This package intelligently combines multiple free forex APIs:

The package automatically selects the appropriate source based on the requested date and currency pair.

Getting Started #

Installation #

Add to your pubspec.yaml:

dependencies:
  forex_currency_conversion_historical: ^1.0.0

Then run:

dart pub get

Usage #

Fetch Today's Rate #

import 'package:forex_currency_conversion_historical/forex_currency_conversion_historical.dart';

void main() async {
  final rate = await fetchForex('USD', 'EUR');
  print('1 USD = $rate EUR');
}

Fetch Historical Rates #

final rate = await fetchForex('GBP', 'JPY', date: '2023-06-15');
print('GBP/JPY on 2023-06-15: $rate');

If you don't have a string representation of the date, you can pass in your DateTime variable and the package will convert it to a YYYY-MM-DD string for you. In this case use fetchForexParseDate.

Safely avoid Precision Errors (Floating point Errors) #

This package returns decimal instead of double to ensure precision in financial calculations. As such you should avoid double at all costs!

Here is an illustration of the problem:

// With double (problematic)
double rate = 0.1 + 0.2; // = 0.30000000000000004 ❌

// With Decimal (precise)
Decimal rate = Decimal.parse('0.1') + Decimal.parse('0.2'); // = 0.3 ✅

License #

Apache 2.0 LICENSE