OAuth is a delegated token authentication method that enables secure access to external data without sharing user credentials, commonly used across websites and applications. While integrating OAuth with blockchain smart contracts might initially seem challenging, Chainlink external adapters streamline this process by handling complex computations off-chain. This approach is particularly efficient for interacting with secure APIs from smart contracts, such as those built using Solidity. The article provides a detailed example of building a Reddit external adapter using Node.js, demonstrating how to utilize existing OAuth handlers and Chainlink’s framework to facilitate secure data interactions between blockchain and Web2 services. By employing external adapters, developers can enhance smart contract functionality with OAuth, ensuring more gas-efficient and seamless integration of off-chain data sources. Additionally, readers are encouraged to explore further resources and engage with technical communities to advance their understanding and application of these integrations.