Frankfurter is a free, open-source currency data API that tracks reference exchange rates published by the European Central Bank.

No usage caps or API keys. Works great client-side in the browser or mobile apps. The public API is available at api.frankfurter.dev. If preferred, you can self-host.

API Endpoints

Frankfurter provides endpoints to retrieve latest rates, historical data, or time series.

Latest Rates
Fetch the latest working day's rates, updated daily around 16:00 CET. 
/* curl -s https://api.frankfurter.dev/v1/latest */
{
  "base": "EUR",
  "date": "2024-11-25",
  "rates": {
    "AUD": 1.6111,
    "BGN": 1.9558,
    "BRL": 6.0941,
    "CAD": 1.4648,
    "...": "..."
  }
}
Change the base currency using the base parameter. The default is EUR. 
/* curl -s https://api.frankfurter.dev/v1/latest?base=USD */
{
  "base": "USD",
  "date": "2024-11-25",
  "rates": {
    "AUD": 1.5351,
    "BGN": 1.8636,
    "BRL": 5.8067,
    "CAD": 1.3957,
    "...": "..."
  }
}
Limit the response to specific target currencies.
/* curl -s https://api.frankfurter.dev/v1/latest?symbols=CHF,GBP */
{
  "base": "EUR",
  "date": "2024-11-25",
  "rates": {
    "CHF": 0.9324,
    "GBP": 0.83465
  }
}
Historical Rates
Retrieve rates for a specific date.
/* curl -s https://api.frankfurter.dev/v1/1999-01-04 */
{
  "base": "EUR",
  "date": "1999-01-04",
  "rates": {
    "AUD": 1.91,
    "CAD": 1.8004,
    "CHF": 1.6168,
    "CYP": 0.58231,
    "...": "..."
  }
}
Change the base currency and filter target currencies.
/* curl -s https://api.frankfurter.dev/v1/1999-01-04?base=USD&symbols=EUR */
{
  "base": "USD",
  "date": "1999-01-04",
  "rates": {
    "EUR": 0.84825
  }
}
Note: Frankfurter stores dates in UTC. If you use a different time zone, be aware that you may be querying with a different calendar date than intended. Also, data returned for today is not stable and will update if new rates are published.
Time Series Data
Fetch rates over a period.
/* curl -s https://api.frankfurter.dev/v1/2000-01-01..2000-12-31 */
{
  "base": "EUR",
  "start_date": "1999-12-30",
  "end_date": "2000-12-29",
  "rates": {
    "1999-12-30": {
      "AUD": 1.5422,
      "CAD": 1.4608,
      "CHF": 1.6051,
      "CYP": 0.57667,
      "...": "..."
    },
    "2000-01-03": {
      "AUD": 1.5346,
      "CAD": 1.4577,
      "CHF": 1.6043,
      "CYP": 0.5767,
      "...": "..."
    },
    "2000-01-04": {
      "AUD": 1.5677,
      "CAD": 1.4936,
      "CHF": 1.6053,
      "CYP": 0.5775,
      "...": "..."
    },
    "2000-01-05": {
      "AUD": 1.5773,
      "CAD": 1.5065,
      "CHF": 1.606,
      "CYP": 0.5778,
      "...": "..."
    },
    "...": "..."
  }
}
Fetch rates up to the present.
/* curl -s https://api.frankfurter.dev/v1/2024-01-01.. */
{
  "base": "EUR",
  "start_date": "2023-12-29",
  "end_date": "2024-11-25",
  "rates": {
    "2023-12-29": {
      "AUD": 1.6263,
      "BGN": 1.9558,
      "BRL": 5.3618,
      "CAD": 1.4642,
      "...": "..."
    },
    "2024-01-02": {
      "AUD": 1.6147,
      "BGN": 1.9558,
      "BRL": 5.3562,
      "CAD": 1.4565,
      "...": "..."
    },
    "2024-01-03": {
      "AUD": 1.6236,
      "BGN": 1.9558,
      "BRL": 5.3859,
      "CAD": 1.4574,
      "...": "..."
    },
    "2024-01-04": {
      "AUD": 1.628,
      "BGN": 1.9558,
      "BRL": 5.3761,
      "CAD": 1.4603,
      "...": "..."
    },
    "...": "..."
  }
}
Tip: Filter currencies to reduce response size and improve performance. 
/* curl -s https://api.frankfurter.dev/v1/2024-01-01..?symbols=USD */
{
  "base": "EUR",
  "start_date": "2023-12-29",
  "end_date": "2024-11-25",
  "rates": {
    "2023-12-29": {
      "USD": 1.105
    },
    "2024-01-02": {
      "USD": 1.0956
    },
    "2024-01-03": {
      "USD": 1.0919
    },
    "2024-01-04": {
      "USD": 1.0953
    },
    "...": "..."
  }
}
Available currencies
Get supported currency symbols and their full names.
/* curl -s https://api.frankfurter.dev/v1/currencies */
{
  "AUD": "Australian Dollar",
  "BGN": "Bulgarian Lev",
  "BRL": "Brazilian Real",
  "CAD": "Canadian Dollar",
  "...": "..."
}
Currency Conversion
Perform currency conversion by fetching the exchange rate and calculating in your code. 
function convert(from, to, amount) {
  fetch(`https://api.frankfurter.dev/v1/latest?base=${from}&symbols=${to}`)
    .then((resp) => resp.json())
    .then((data) => {
      const convertedAmount = (amount * data.rates[to]).toFixed(2);
      alert(`${amount} ${from} = ${convertedAmount} ${to}`);
    });
  }

convert("EUR", "USD", 10);
Click or tap above to execute the code.

Self-Hosting

If you prefer not to use our hosted service, you can self-host with Docker. 

docker run -d -p 8080:8080 \
    --pull always \
    lineofflight/frankfurter