Frankfurter API

Beginner's Pick Currency Exchange / No Auth Required Beginner HTTPS CORS
Free to Use
82 A
Measured Score 0 50 100 Speed 22/30 Consistency 17/20 Security 20/20 Browser access 15/15 Transparency 8/15 TESTED 2026-08-10

Overview

Frankfurter is an open-source currency data API backed by the European Central Bank (ECB) exchange rate dataset, providing rates for 33 major currencies updated every weekday. It supports historical queries, time series ranges, and currency conversion — all without any authentication or rate limits. The API is clean, fast, and CORS-enabled, making it a top choice for hobby and production projects alike.

Beginner Tip

No sign-up required. The live endpoint is `https://api.frankfurter.app/latest` for today's rates. To convert between currencies, add query params: `?from=USD&to=EUR`. For historical data, replace `latest` with a date like `2024-01-15`. All rates are based on the ECB daily reference rate.

Measurement Record

What actually happened when we called this API from our own infrastructure. Every value below was recorded by the request, not copied from the provider's documentation.

Request
GET https://api.frankfurter.app/latest?from=USD&to=EUR,JPY,GBP
Result
HTTP 200 · application/json · 97 bytes · compressed
Response time
62 ms (median of 3) · fastest 56 ms
Transport
TLSv1.3 · TLS_AES_256_GCM_SHA384 · certificate issued by Google Trust Services
Browser CORS
Allowed — Access-Control-Allow-Origin: *
Served by
cloudflare
Recorded
2026-08-10

Fields Returned

Top-level fields present in the response we captured, with the type and value we actually received.

Field Type Value received
amount integer 1
base string USD
date string (date) 2026-08-10
rates object {3 fields}

Captured Response

Captured from a real request to https://api.frankfurter.app/latest?from=USD&to=EUR,JPY,GBP on 2026-08-10. Long arrays and nested objects are truncated to keep the shape readable.

JSON Response · Captured
{
  "amount": 1,
  "base": "USD",
  "date": "2026-08-10",
  "rates": {
    "EUR": 0.86543,
    "GBP": 0.7405,
    "JPY": 158.64
  }
}

Field Reference

amount The base amount used for conversion (default is 1).
base The currency code the rates are expressed relative to.
date The date of the rates in YYYY-MM-DD format (most recent ECB publishing day).
rates Key-value map of currency codes to their exchange rate relative to the base currency.

Implementation Example

Calls a real endpoint of this API. Replace any placeholder credentials with your own key.

Request
const url = "https://www.frankfurter.app/docs";
const response = await fetch(url);
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data);

What Can You Build?

Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.

How This API Fails

We deliberately sent this API a broken request and recorded exactly what came back on 2026-08-10. Knowing the shape of an error before you hit it makes error handling much easier to write.

HTTP 404 Requesting a path that does not exist application/json
{
  "status": 404,
  "message": "not found"
}
HTTP 404 Sending an invalid value for "from" application/json
{
  "message": "not found"
}

Common Errors & Troubleshooting

Generated guidance based on this API's documentation, not observed by us. Treat it as a starting point and check against the provider's own error reference.

400 Bad Request — not found error Requesting a currency not in the ECB dataset (e.g., cryptocurrencies, exotic currencies like THB).
Fetch `/currencies` to see the 33 supported codes. Only ECB-covered currencies are available.
Weekend/holiday data returns last available date The ECB does not publish rates on weekends or EU public holidays.
This is expected behavior. The API automatically returns the most recent available rates — check the `date` field in the response to confirm which date was used.
CORS error when calling the docs URL Using `frankfurter.dev` (the docs site) as the API endpoint instead of the actual API host.
Use `https://api.frankfurter.app` as the base URL for all API calls, not the documentation site.

Measured Score Breakdown

Live HTTP request to the API endpoint

Speed 22/30
Consistency 17/20
Security 20/20
Browser access 15/15
Transparency 8/15
Endpoint Response Time 62ms

Fully tested on Aug 10, 2026

Technical Specifications

Auth No Auth
HTTPS REQUIRED
CORS YES
Difficulty Beginner
Endpoint last called: 2026-08-10

Alternatives to Frankfurter

Technical alternatives for different use cases.

Free, open-source API backed by ECB data

Better For

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