FrankFurter

Frankfurter is an open-source API for current and historical foreign exchange rates published by the European Central Bank. https://www.frankfurter.app/

This library is a C# API for accessing the Frankfurter foreign exchange rate API.

Installation

Install the Nuget package in your .NET application:

nuget install FrankFurter

or in .NET Core applications:

dotnet add package FrankFurter

Quick Use

Client.GetLatestRateAsync()

If you just want to get a latest rate for a currency, use the static GetLatestRateAsync() method:

const string baseCurrency = "USD";
const string targetCurrency = "GBP";
// get the latest USD-GBP rate 
var rate = await Client.GetLatestRateAsync(baseCurrency, targetCurrency);

The date of the rate will be the most recent data available.

Client.GetRateForAsync()

If you need a rate for a specific date, use GetRateForAsync():

var date = new DateTime(2021,8,2);
const string baseCurrency = "USD";
const string targetCurrency = "GBP";
// get the latest USD-GBP rate 
var rate = await Client.GetRateForAsync(date, baseCurrency, targetCurrency);

You can also use the amount parameter to perform conversions.

Usage

Create a Client instance and call the appropriate method. Note that the client implements IDisposable so should be in a using block:

using (var client = new Client())
{
    // call methods
}

GetLatestAsync()

Gets the latest available exchange rates for all available currencies, using EUR as a base.

SingleDate latest = await client.GetLatestAsync();

The SingleDate has a helper method GetRate() which returns the rate for a given currency.

SingleDate latest = await client.LatestAsync();
decimal gbpRate = latest.GetRate("GBP");

GetHistoricalAsync()

Get the rates for a specific date (going back to 4th Jan 1999). If you specify a date for which are not valid, e.g. weekend/holiday, the Frankfurter API will return the nearest date before that.

var forDate = new DateTime(2021,8,2);
SingleDate aug2nd = await client.GetHistoricalAsync(forDate);

GetTimeSeriesAsync()

Get the rates for a range of dates. If you leave the toDate as null it returns all dates upto the latest available date. Note that the resulting date range may not be contiguous as rates are not available for every date.

var fromDate = new DateTime(2021,8,1);
TimeSeries rates = await client.GetTimeSeriesAsync(forDate);

Important! these calls can return a lot of data so you should normally specify just the target currencies you need, e.g.:

// get EUR-USD rate from 1st August 2021 to latest
var fromDate = new DateTime(2021,8,1);
var toFetch = new string[] {"USD"};
TimeSeries rates = await client.GetTimeSeriesAsync(fromDate, toCurrencies: toFetch);

For a specific set of dates, provide both a fromDate and toDate:

var fromDate = new DateTime(2021,8,2);
var toDate = new DateTime(2021,8,27);
var toFetch = new string[] {"USD"};
TimeSeries rates = await client.GetTimeSeriesAsync(fromDate, toDate, toCurrencies: toFetch);

GetCurrenciesAsync()

https://www.frankfurter.app/docs/#timeseries

Returns a dictionary of the ISO 4217 currency codes and descriptions supported by the Frankfurter API.

Dictionary<string, string> currencies = await client.GetCurrenciesAsync();
// get name for USD:
var usdName = currencies["USD"];   // "United States Dollar"

Common Parameters

These parameters can be used in all methods except GetCurrenciesAsync

baseCurrency

To query for a different base currency use the baseCurrency parameter:

SingleDate latest = await client.LatestAsync(baseCurrency:"GBP");

toCurrencies

By default the method returns all available currencies: you should normally specify just the currency codes you need, e.g. to fetch just EUR-GBP and EUR-USD

var toFetch = new string[] {"GBP", "USD"};
SingleDate latest = await client.LatestAsync(toCurrencies: toFetch);

amount

The default amount of the base currency is normally 1. You can change this with the amount parameter.

// convert €100 to all currencies
SingleDate latest = await client.LatestAsync(amount: 100m);

Requirements

Any application that supports .NET Standard 2.0 - this includes .NET Framework 4.6.1 and later, .NET Core 2.0 + and .NET 5 and .NET 6