Card endpoints use the same base URL and API key as the rest of the API, and are signature-gated: sendX-Numero-SignatureandX-Numero-Signature-Version: v2as well. See Request signing.
Cards
Set Card Limits
Set per-card daily and per-transaction spend limits.
Set a card’s daily and per-transaction spend limits (USD). Either field may be sent on its own.
Signature required: Yes