Chainlink

Chainlink is a decentralized oracle network that enables smart contracts to securely access off-chain data feeds, web APIs, and traditional bank payments. It is well known for providing highly secure and reliable oracles to large enterprises (Google, Oracle, and SWIFT) and leading smart contract development teams such as Polkadot/Substrate, Synthetix, Loopring, Aave, OpenLaw, Conflux, and many others.