> ## Documentation Index
> Fetch the complete documentation index at: https://docs.rheon.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Card rate

> GET /v1/card/rate - the live card rate, in either direction.

Returns the live rate for a card payment, in both directions: `buy` prices
paying fiat by card to receive crypto, `sell` prices the reverse. Use it for
display - a ticker, a slider, a "you receive" preview. When the buyer commits,
go through [`POST /v1/card/quote`](/api-reference/card-quote), which returns the
full fee breakdown for the exact amount.

## Request

<ParamField query="fiatCurrency" type="string" required>
  ISO 4217 code, e.g. `EUR`.
</ParamField>

<ParamField query="cryptoCurrency" type="string" required>
  The crypto asset, e.g. `USDC`.
</ParamField>

<ParamField query="amount" type="string" required>
  The fiat amount to price, as a decimal string. Rates depend on the amount - a
  flat fee minimum makes small amounts more expensive per unit - so price the
  real amount rather than extrapolating from one sample.
</ParamField>

<ParamField query="side" type="string">
  `buy` (fiat to crypto, the default) or `sell` (crypto to fiat).
</ParamField>

## Response

<ResponseField name="side" type="string">
  Echo of the direction priced.
</ResponseField>

<ResponseField name="fiatCurrency" type="string">
  Echo of the fiat currency.
</ResponseField>

<ResponseField name="cryptoCurrency" type="string">
  Echo of the crypto asset.
</ResponseField>

<ResponseField name="fiatAmount" type="string">
  The fiat side of the conversion, fees included.
</ResponseField>

<ResponseField name="cryptoAmount" type="string">
  The crypto side of the conversion at this rate, as a decimal string. Keep it
  as a string - precision follows the asset.
</ResponseField>

<ResponseField name="rate" type="string">
  The rate used, in fiat per unit of crypto.
</ResponseField>

<Warning>
  This is a live rate, not a hold. Nothing is reserved and the figure moves with
  the market. The number a buyer commits to comes from
  [`/v1/card/quote`](/api-reference/card-quote).
</Warning>

<RequestExample>
  ```bash cURL theme={null}
  curl "$RHEON_API/v1/card/rate?fiatCurrency=EUR&cryptoCurrency=USDC&amount=100.00&side=buy" \
    -H "Authorization: Bearer $RHEON_API_KEY"
  ```
</RequestExample>

<ResponseExample>
  ```json 200 theme={null}
  {
    "side": "buy",
    "fiatCurrency": "EUR",
    "cryptoCurrency": "USDC",
    "fiatAmount": "100.00",
    "cryptoAmount": "108.139535",
    "rate": "0.86"
  }
  ```
</ResponseExample>

## Errors

| HTTP | `code`            | When                                                                                |
| ---- | ----------------- | ----------------------------------------------------------------------------------- |
| 400  | `invalid_request` | Missing or malformed amount, an unsupported currency, or `side` not `buy` / `sell`. |
| 401  | `unauthorized`    | Missing, malformed, or unknown API key.                                             |
| 429  | `rate_limited`    | Over your key's rate limit.                                                         |
| 502  | `upstream_error`  | The card partner is unavailable.                                                    |
| 500  | `internal`        | Unexpected server error.                                                            |