frankfurter.historical

stable Standard

ECB reference rates on a past date.

GET /v1/frankfurter/historical

What you get#

One Frankfurter record in Onekey's unified shape, in data. If the record does not exist you get a 404 not_found and are not charged.

What it costs#

Standard · 1 credit for a fresh fetch, charged only when it succeeds.
Free when served from cache (0.2 credit for a cached response over 100 KB).
Free if the request is invalid (never charged) or the source fails or reports not found (refunded).

Parameters#

Name	Type	Required	Default	What it is	Constraints
`date`	string	yes	(required)	Date YYYY-MM-DD	max 10 chars; must match `\d{4}-\d{2}-\d{2}`; trimmed
`base`	string	no	`eur`	Base currency (ISO 4217), e.g. usd	max 3 chars; must match `[A-Za-z]{3}`; trimmed, lowercased

Request#

curl "https://api.onekey.dev/v1/frankfurter/historical?date=2024-01-02&base=usd" \
  -H "x-api-key: YOUR_API_KEY"

Try it

Add your key to run this call right here. No key? Get one free. The key stays in this tab.

Recorded response#

A real Frankfurter response, recorded and returned in Onekey's shape. Fields the platform does not provide are null.

json

{
  "success": true,
  "data": {
    "market": {
      "symbol": "USD"
    },
    "entity": {
      "date": "2024-01-02T00:00:00Z"
    },
    "ext": {
      "amount": 1,
      "rates": {
        "AUD": 1.4738,
        "BGN": 1.7851,
        "BRL": 4.8888,
        "CAD": 1.3294,
        "CHF": 0.84931,
        "CNY": 7.1435,
        "CZK": 22.533,
        "DKK": 6.8046,
        "EUR": 0.91274,
        "GBP": 0.79085,
        "HKD": 7.8139,
        "HUF": 348.76,
        "IDR": 15524,
        "ILS": 3.624,
        "INR": 83.32,
        "ISK": 137.55,
        "JPY": 142.1,
        "KRW": 1313.23,
        "MXN": 17.058,
        "MYR": 4.6025,
        "NOK": 10.2971,
        "NZD": 1.5947,
        "PHP": 55.66,
        "PLN": 3.9894,
        "RON": 4.5368,
        "SEK": 10.1812,
        "SGD": 1.3265,
        "THB": 34.285,
        "TRY": 29.726,
        "ZAR": 18.5889
      }
    }
  },
  "metadata": {
    "platform": "frankfurter",
    "endpoint": "historical",
    "cached": false,
    "stale": false,
    "age_s": 0,
    "fetched_at": "2026-01-01T12:00:00+00:00",
    "credits_charged": 1,
    "request_id": "7f3a9c2e5b1d4c8fa2e6d0b9c4f18e37"
  },
  "error": null
}

Field mapping#

How this endpoint's source fields become Onekey's unified schema. Fields the source lacks come back as null.

Source path	Onekey field	Transform
`base`	`market.symbol`	-
`date`	`entity.date`	`toIsoDate`
`amount`	`ext.amount`	`toNumber`
`rates`	`ext.rates`	-

Caching and freshness#

Fresh for about 1 hour. Repeat calls in that window are served from cache and are free.
Between 1 hour and 1 day the cached copy is still served instantly and marked stale: true while Onekey refreshes it in the background.
If the source is down when a refresh is needed, the last copy can be served for up to 1 day more (marked stale).
A "not found" is remembered for 5 minutes and is free.
The cache is shared across all customers, which is what keeps repeat calls cheap.

What can go wrong#

Status	Code	What to do
401	`unauthorized`	Check the `x-api-key` header.
402	`insufficient_credits`	Add credits; your balance must cover the price.
404	`not_found`	That record does not exist. Free; do not retry.
422	`invalid_params`	Fix the parameters using the table above. Free.
429	`rate_limited`	Wait `Retry-After` seconds, then retry.
502	`upstream_error`	The source failed. Refunded; retry with backoff.

See Errors for the full list and retry guidance.

Status: stable (verified against the live source).