Skip to main content

Crypto Sandwitch — Fiat → Crypto → Fiat Rails (Fintech-Operated)

Overview​

Crypto Sandwitch is a fiat–crypto–fiat payments rail operated by a fintech platform, without direct EMI involvement. End customers always start and end in fiat currency, while the fintech uses crypto (e.g., stablecoins) purely as a settlement and liquidity rail between fiat endpoints.

The key idea:

  • Fiat in — user (or merchant) funds in local fiat via bank transfer/card/instant payments to the fintech.
  • Crypto in the middle — fintech converts fiat to crypto on an exchange or via an OTC/LP, and moves value on-chain.
  • Fiat out — on the other side of the corridor, the fintech (or its partners) off-ramp crypto back to local fiat and pay out to the target bank / wallet.

From the end user’s perspective, this looks like a fast, cheap, cross-border (or domestic) fiat payment product. The crypto “sandwich layer” in the middle is abstracted away; the user never needs to hold or manage crypto directly.

Key properties:

  • Abstracted crypto UX: Customers never touch private keys or on-chain addresses; they interact with a normal fintech app (balances, IBANs, cards, etc.).
  • Modular rails: The fintech can plug into different exchanges, LPs, and payout partners per jurisdiction, while keeping a consistent product surface.

Actors​

ActorRoleRegulated?
End Customer / PayerInitiates a payment in local fiat. Sees only fiat balances and FX rates in the app.KYC’d by the fintech
Recipient / MerchantReceives funds in local fiat (e.g., payout to bank account or wallet).KYB’d / KYC’d by the fintech (use-case dependent)
Fintech PlatformOrchestrates the entire flow, holds customer balances, manages FX, and handles crypto.Yes — PSP / VASP / local fintech licenses
Crypto Liquidity Provider / CEXExecutes fiat↔crypto conversions and on-chain transfers on behalf of the fintech.Yes — jurisdiction-dependent (VASP / MSB)
Fintech PartnersProvide fiat collection and payout rails on both ends of the corridor.Yes — PSD2 / local PSP frameworks
EMI (optional partner)Provides stablecoin infra, privacy, can act as on/off rampYes — EMI license

The fintech can:

  • Use public stablecoins (e.g., USDC, EURC) as the crypto leg, or
  • Integrate with on/off-ramp providers that manage token issuance and compliance, or

Flow Summary (High-Level)​

Business Case for ZKP-integration​

Fintechs can partner with an EMI that provides MICA-compliant, private stablecoin infrastructure. Value proposition:

  • Hide business information on fintech operations and treasury
  • Do not leak customer data — volume, relationships, and other business metrics
  • Offloading compliance — private rails where EMI takes care of the necessary compliance
  • One SDK to build your product on top - simple integration, covering all needs
  • Future: one product to manage crypto and fiat - request payment links, bank account conneced with on-chain account, e-money swap

Examples​