Quote Currency

Overview

Quote Currency provides the denominator in a price pair. If one BTC is quoted at a number of USD, BTC is the base asset in that market pair and USD is the quote currency. The naming should not be confused with a merchant’s Base Fiat Currency.

Payment APIs can accept an invoice amount in a fiat or crypto currency and calculate the required Pay Currency amount. The rate record should identify both sides of the pair, its source, precision, and timestamp.

Quote currency can match Display Currency when the customer sees the same fiat unit used for conversion. However, an interface can display a localized amount while the backend quote uses another reference and performs an additional conversion.

Rates are time-sensitive. The calculated crypto amount is valid only through the defined Quote Expiration. After expiry, the system should create a new quote rather than reuse a stale pay amount.

Reconciliation must preserve the quote pair and rate direction. Confusing asset-per-fiat with fiat-per-asset can produce severe amount errors even when the numeric rate appears plausible. APIs should use explicit field names and examples.

Rate providers can express the same pair in either direction, so internal systems should store canonical pair names and conversion formulas. The quoted rate should never be inferred from display text. Validation should include positive values, expected magnitude, source freshness, and consistency with the calculated pay amount before the quote is shown to a payer.

Quote services should reject unsupported or ambiguous currency codes and should preserve the provider’s rate identifier where available. A fallback rate source needs explicit priority and must not silently change the economic terms of an active payment.