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GET
/
v1
/
fx
/
rate
Retrieve an indicative rate
curl --request GET \
  --url https://api.antonpayments.com/v1/fx/rate \
  --header 'Authorization: Bearer <token>' \
  --header 'DPoP: <api-key>'
{
  "sell_currency": "USD",
  "buy_currency": "USD",
  "mid_market_rate": "1234.56",
  "customer_rate": "1234.56",
  "fx_markup_bps": 123,
  "sell_amount": "1234.56",
  "buy_amount": "1234.56",
  "rate_timestamp": "2026-04-15T14:30:00Z"
}

Documentation Index

Fetch the complete documentation index at: https://docs.antonpayments.com/llms.txt

Use this file to discover all available pages before exploring further.

Authorizations

​
Authorization
string
header
required

OAuth 2.0 client_credentials grant (RFC 6749 §4.4) bound to a DPoP keypair (RFC 9449).

Flow (every authenticated /v1 call requires both an access token AND a fresh per-request DPoP proof):

  1. Register a credential via the merchant portal. Anton issues a client_id (ant_oc_<env>_<32hex>) and a client_secret (ant_ocs_<env>_<48hex>, shown ONCE). The portal generates an ES256 or Ed25519 DPoP keypair in your browser; you store the private half.
  2. Mint an access token: POST /oauth/token with Authorization: Basic <client_id:client_secret> and Content-Type: application/x-www-form-urlencoded. Body: grant_type=client_credentials. A DPoP header carrying a proof signed for the token endpoint is required (no ath claim on this proof).
  3. Use the token: send Authorization: DPoP <access_token> plus a fresh DPoP: <proof> header on every /v1 request. The proof JWT MUST carry htm (request method), htu (request URL, no query/fragment), iat (within ±60s), jti (unique within 5 min), and ath (SHA-256 of the access token, base64url).

Tokens expire in 1 hour in production / staging and 8 hours in sandbox. There are no refresh tokens — call /oauth/token again with your secret. Anton's public signing key is published at /.well-known/jwks.json.

OpenAPI 3.0 has no native DPoP scheme; this declaration plus dpopHeader together convey both the access-token Authorization and the per-request proof header.

​
DPoP
string
header
required

Per-request DPoP proof JWT (RFC 9449). MUST accompany the Authorization: DPoP <access_token> header on every protected operation. The proof is signed by the merchant's private DPoP key and carries htm, htu, iat, jti, and ath claims.

Query Parameters

​
sell_currency
string
required

ISO 4217 three-letter currency code.

Pattern: ^[A-Z]{3}$
Example:

"USD"

​
buy_currency
string
required

ISO 4217 three-letter currency code.

Pattern: ^[A-Z]{3}$
Example:

"USD"

​
sell_amount
string

Optional — amount to convert. When present, the response includes a buy_amount. Decimal amount as a string, never a float. Up to 12 whole digits.

Pattern: ^-?\d{1,12}(\.\d+)?$
Example:

"1234.56"

Response

Indicative rate.

​
sell_currency
string
required

ISO 4217 three-letter currency code.

Pattern: ^[A-Z]{3}$
Example:

"USD"

​
buy_currency
string
required

ISO 4217 three-letter currency code.

Pattern: ^[A-Z]{3}$
Example:

"USD"

​
mid_market_rate
string
required

Decimal amount as a string, never a float. Up to 12 whole digits.

Pattern: ^-?\d{1,12}(\.\d+)?$
Example:

"1234.56"

​
customer_rate
string
required

Mid-market adjusted by your pricing plan's FX markup.

Pattern: ^-?\d{1,12}(\.\d+)?$
Example:

"1234.56"

​
fx_markup_bps
integer
required

Markup applied to mid-market, in basis points.

​
sell_amount
string

Decimal amount as a string, never a float. Up to 12 whole digits.

Pattern: ^-?\d{1,12}(\.\d+)?$
Example:

"1234.56"

​
buy_amount
string

Decimal amount as a string, never a float. Up to 12 whole digits.

Pattern: ^-?\d{1,12}(\.\d+)?$
Example:

"1234.56"

​
rate_timestamp
string<date-time>

RFC 3339 / ISO 8601 timestamp in UTC.

Example:

"2026-04-15T14:30:00Z"