Overview
The Rate endpoint returns the exchange rate for a currency pair with your
platform fee already applied on top. Use it to show your users what a conversion
will cost before they commit to it.
The rate is indicative — it does not reserve or lock a quote, and no funds
move. Pass exactly one of source_amount or destination_amount; Superbank
computes the other side.
Endpoints
Object
Attributes
| Attribute | Description |
|---|
source_currency | The currency code being converted from. |
destination_currency | The currency code being converted to. |
mid_market_rate | Destination units per one source unit, before any fee. |
inverted_mid_market_rate | The inverse of mid_market_rate, for convenience. |
effective_rate | The all-in rate the recipient actually receives per source unit, after the fee. |
source_amount | The amount debited in the source currency. |
destination_amount | The amount credited in the destination currency. |
fee | The fee applied on top of the exchange rate. |
fee.total | The total fee for this conversion, denominated in the source currency. This is a single all-in figure. |
fee.currency | The currency the fee is denominated in (the source currency). |
fee.total is the complete cost of the conversion. It equals the gap between
what is debited and what would be received at the mid-market rate
(source_amount - destination_amount / mid_market_rate), so the difference
between mid_market_rate and effective_rate is fully explained by it.
GET /v0/rates
Parameters
| Query parameter | Description |
|---|
source_currency_code | Required. The currency to convert from, e.g. USDC, USD. |
source_rail | Required. The source rail, e.g. SOLANA, ACH. |
destination_currency_code | Required. The currency to convert to, e.g. CAD, USDC. |
destination_rail | Required. The destination rail, e.g. LOCAL, RTP. |
destination_country_code | The ISO 3166-1 alpha-2 country code of the destination. Required when the destination is fiat. |
source_country_code | The ISO 3166-1 alpha-2 country code of the source. Required when the source is fiat (on-ramp). |
source_amount | The amount in the source currency. Mutually exclusive with destination_amount. |
destination_amount | The amount in the destination currency. Mutually exclusive with source_amount. |
At least one leg must be a stablecoin — fiat-to-fiat pairs are not supported.
Stablecoin legs use a crypto rail (SOLANA, ETHEREUM, POLYGON, TRON);
fiat legs use ACH, RTP, DOMESTIC_WIRE, or LOCAL.
Request
curl --request GET \
--url 'https://api-sandbox.superbank.co/v0/rates?source_currency_code=USDC&source_rail=SOLANA&destination_currency_code=CAD&destination_rail=LOCAL&destination_country_code=CA&source_amount=1000' \
--header 'X-Api-Key: YOUR_API_KEY'
Response
{
"source_currency": "USDC",
"destination_currency": "CAD",
"mid_market_rate": 1.3788512205,
"inverted_mid_market_rate": 0.7252415072,
"effective_rate": 1.3651,
"source_amount": 1000,
"destination_amount": 1365.1,
"fee": {
"total": 9.97,
"currency": "USDC"
}
}
Errors
| Status | When |
|---|
400 | Both or neither of source_amount / destination_amount were provided. |
400 | An unsupported currency, a rail that doesn’t match the currency, or a fiat-to-fiat pair. |
400 | A fiat leg without its country code. |
401 | Missing or invalid API key. |
