Currency conversion API
Convert one positive decimal amount with one selected rate.
REST and fx_convert_currency return the same amount, rate, result, timestamp, freshness, and market session.
Request
REST
curl --request GET \
--url "https://api.narwhalapi.com/v1/fx/convert?from=USD&to=JPY&amount=100.00" \
--header "Authorization: Bearer $NARWHAL_API_KEY"| Parameter | Rule |
|---|---|
from | Required source currency. |
to | Required target currency. It must differ from from. |
amount | Positive decimal string up to 1000000000000. |
Response
200 OK
{
"from": "USD",
"to": "JPY",
"amount": "100.00",
"rate": "147.23",
"converted": "14723",
"market_session": "open",
"timestamp": "2026-08-22T06:29:39Z",
"stale": false
}Rounding
Narwhal uses decimal arithmetic and rounds once to the target currency's ISO 4217 minor unit using half-even rounding.
Errors
Invalid pairs or amounts return 400 invalid_query. Unsupported currencies return 404 currency_not_supported.