Cardstack is an open source protocol supported by blockchain. It was announced today that it will integrate Chainlink into Card payment —A consumer-oriented encrypted payment and reward platform. Cardstack will start with the xDAI chain and use Chainlink Price Feeds to establish an accurate and tamper-proof exchange rate on the platform; however, it plans to expand to other blockchains and second-layer solutions.

Today, most DeFi price feeds are used for trading and financial product use cases, focusing on the needs of investors, token holders or market makers. However, as encryption technology has received more and more mainstream attention; especially since layer 2 and other blockchain innovations have made many scalability solutions possible, payment use cases have become more and more important.

This is why Cardstack has developed a multi-party payment protocol. Card Pay is built as part of the Cardstack suite of decentralized SaaS. It supports prepaid cards and reward cards for making purchases on the network and earning reward tokens.

The Card Pay protocol makes full use of the composability of DeFi, including the use of stablecoins as a medium of exchange, and the use of web3 wallets as an interface for checking balances and authorizing payments. Customers can use a dedicated mobile application to easily contact the merchant, just scan the QR code (supported by WalletConnect) and confirm the transaction via Face ID or Touch ID.

Card payment + link

Exchange rates are important in payment use cases because they ensure that customers and merchants can find a path from the tokens held by the customer to the currency accepted by the merchant. The Chainlink Oracle network offers many types of exchange rates-from local tokens such as ETH to stable currencies such as DAI and legal currencies such as USD, as well as emerging community and governance tokens.

Used in conjunction with decentralized exchanges such as Linkswap, Chainlink enables Cardstacl to provide seamless one-click payments from customers’ wallets. The latest Chainlink price feed update will be used to calculate the number of tokens transferred from customers to merchants without requiring a separate exchange step to process payments.

Chainlink is the most commonly used decentralized Oracle solution in DeFi and cross-blockchain, and has secured billions of dollars in value. Chainlink Price Feeds provides a variety of time-tested design features that not only ensure accurate exchange rates, but also provide strong protection against unexpected events.

Some of these features include:

• High-quality data — Chainlink Price Feed obtains source data from many advanced data aggregators such as BraveNewCoin and Kaiko, resulting in price data (weighted by transaction volume) aggregated by hundreds of exchanges and removed from outliers and wash transactions. This can generate accurate global market prices that can withstand data manipulation attacks such as API downtime, flash memory crash abnormal values, and flash memory lending.
• Secure Node Operator — Chainlink Price Feeds are protected by independent, security-reviewed and Sybil-resistant oracle nodes operated by leading blockchain DevOps teams, data providers and traditional enterprises. Even under extreme network conditions, Chainlink nodes have a good record of reliability.
• Decentralized network — Chainlink Price Feeds are scattered at the data source, oracle node and oracle network level, thereby providing strong protection against downtime and tampering of the data provider or oracle network.
• Transparent system — Chainlink provides a powerful reputation framework and a set of on-chain monitoring tools that allow users to independently verify the historical performance of the node operator and the oracle network, as well as check the real-time prices provided.

Cardstack aims to use Chainlink’s blockchain-agnostic features to integrate its Price Feed across multiple blockchains and smart contract platforms. In this way, even if customers and merchants buy and sell through two different networks or blockchains, they can use the same exchange rate.

Combining it with layer 2 interoperability technologies such as state channels can provide a user experience for customer payments, just like those provided by centralized payment applications such as Square’s Cash App, WeChat App, and Alipay. It is relaxed and friendly.

With the development of the crypto ecosystem, we expect to see more types of tokens or assets, whether they are linked to real-world currencies or to the predetermined value of the community. We look forward to continuing to work with Chainlink to use its shared Oracle infrastructure to bring the value of decentralized payments and commerce to the mass market using a secure decentralized Oracle. “
– Chris Tse, founding director of Cardstack