Today Breez announces FiatLink, an open API standard for the integration of on and off ramps directly inside of Lightning wallets and applications. Currently there are many issues with seamless integration of Bitcoin to fiat exchanges inside of applications, chief among them being lack of Lightning support by many brokerages. In addition to that, each brokerage service in the market builds proprietary APIs for integration with their services, increasing the overhead of integration of multiple options by application and wallet developers. Breez SDK’s support for the FiatLink API can facilitate a single solution to both problems.
FiatLink, as an open interface standard, would also allow seamless integration of multiple brokerage options inside a Lightning application or wallet. Rather than have to independently integrate each option’s individual API, any brokerage service that has integrated FiatLink would be usable within an application with no extra development overhead. This can help foster an interoperable ecosystem of multiple brokers and multiple applications all seeking the optimal price point in order matching between users needing to acquire fiat or Bitcoin. Swiss Bitcoin operations, such as Relai and Pocket Bitcoin, were consulted in tailoring the API design to meet the needs of existing brokerage services.
Multiple payment options (SEPA, credit cards, and bank transfers) are supported. API providers allow users to request price and cost estimates, final quotes, and then finally confirm a specific order quote and finalize it by inputting their payment information. In Switzerland, users are able to make transactions up to 1000 CHF (Swiss Franc) in value per transaction between Swiss brokerages and regulated non-Swiss banks without requiring additional KYC beyond the payment method.
Withdrawals from a brokerage service to the users wallet is processed through LNURL-Withdraw. This is a function in the LNURL protocol that allows a static QR code to be saved and scanned by the user at their leisure, negotiating in the background over HTTP providing an actual Lighting invoice to receive their Bitcoin. It allows an optional on-chain address to be included to facilitate withdrawal on-chain if it fails to process over Lightning for any reason.
The API does support Address Ownership Proof Protocol (AOPP) required by some jurisdictions under the Travel Rule, but in the case of Lightning wallet and applications can generate a random Lightning node pubkey to use for a single withdrawal.
FiatLink, if widely adopted, could offer a competitive and streamlined solution to integrating fiat to Bitcoin transfers for wallet and application developers to integrate.
Source: https://bitcoinmagazine.com/technical/breez-announces-fiatlink-a-lightning-to-fiat-api-standard