FX Services

What can FX Services do?

FX Services let you convert an amount in one currency or asset into another and deliver the result to a destination of your choosing. A single conversion can move value across very different rails — for example, pulling USDC from a DLT wallet and delivering Bahamian dollars (BSD) to a bank account.

The core model is Quote & Capture, a two-step flow:

Quote — POST /fx/quote. You describe the conversion (currencies, amount, participants, and how funds are sourced and delivered). Movmint prices it at the current market rate plus your client-specific spread and fees, locks that rate, and returns a quote_id with an expiry.
Capture — POST /fx/quote/capture/{quote_id}. Before the quote expires, you capture it to execute the transaction at the locked rate and receive funding/delivery instructions.

sequenceDiagram
    participant App as Your Application
    participant API as Movmint FX API
    App->>API: POST /fx/quote (currencies, amount, participants, configs)
    API-->>App: quote_id + quoted_amount + valid_until
    Note over App: Decide to proceed before valid_until
    App->>API: POST /fx/quote/capture/{quote_id}
    API-->>App: transaction_id + status + source_funding_instructions

Supported currencies and assets

Conversions are directional and limited to the corridors (Products) in your subscription. Across the platform, FX Services work with fiat (USD, CAD, BSD, Sand Dollar), stablecoins (USDC, EURC), and crypto (BTC, ETH). The exact pairs available to you are defined by your Product subscription.

Funding and delivery rails

Both the source (where funds come from) and the target (where converted funds go) are configured per transaction. Four rail types are supported:

Type	As source	As target	Notes
`BANK_ACCOUNT`	Pull via bank rails, or push from bank rails to Movmint	Deliver via US ACH/US FedNow/Local RTGS
`CARD`	N/A	Push-to-card	Cannot pull funds from a Debit card at this time
`DLT_WALLET`	On-chain transfer in	On-chain transfer out
`CLIENT_BALANCE`	Debit a prefunded balance (instant)	Credit a prefunded balance (instant) at Movmint

Pricing models

The quote_model field controls which side of the conversion is fixed:

fixed_source (default) — you fix the source amount; Movmint calculates the target amount at the current rate.
fixed_target — you fix the target amount; Movmint calculates the required source amount.

Pricing (market rate, spread in basis points, and fees) is identical regardless of the funding/delivery rails you choose.

Quote & Capture vs. FlowLink

FX Services (Quote & Capture) are interactive: you see and approve a locked rate before executing. If you instead want deposits to convert and deliver automatically at market rate with no per-transaction approval, use FlowLink.

Aspect	Quote & Capture	FlowLink
Pricing	Rate locked at quote time	Market rate at deposit time
Approval	Required (the capture step)	Pre-authorized at creation
Deposit address	Ephemeral, per transaction	Persistent, reusable
Destination	Chosen per transaction	Immutable, set at creation
Flow	Interactive, multi-step	Automated, straight-through

In this section

Quote — request a quote: required fields, address requirements, and source/destination funding configuration.
Capture — capture a quote to execute, and understand when funds are delivered.

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Idempotency
Both /fx/quote and /fx/quote/capture/{quote_id} require an x-idempotency-key header (a UUID you generate). Reuse the same key when retrying a request to guarantee at-most-once processing.