ChainLink is a decentralised oracle service which enables smart contracts to securely access off-chain data feeds, web APIs, and traditional bank account payments. Chainlink is well known for providing highly secure and reliable oracles to both large enterprises (SWIFT) and leading smart contract development teams.
Chainlink aims to ensure that external information and off-chain computations are reliable and secure. To do this, Chainlink makes use of secure hardware such as Intel's SGX to construct a Trusted Execution Environment (TEE). Within the TEE, code is executed in an unbiased state where untrusted actors within the system are unable to access or corrupt information.
It provides the infrastructure for building decentralised applications, or dApps, with a focus on security and accessibility of data for any type of user. Chainlink uses its LINK token as an incentive mechanism between participating nodes in the system: if one node doesn't do what it's supposed to, another will get paid out instead. This creates a high level of trust within the network and incentivises participation by anyone who wants to earn from providing an API endpoint oracle service.
The Chainlink network is driven by a open-source protocol developed by Chainlink Labs (formerly Smart Contract Ltd), which was founded in 2014 by Sergy Nazarov and Steve Ellis.
The Chainlink protocol went live on the Ethereum mainnet in 2019 and has since expanded to support additional blockchains such as Polygon, BSC and more.
Chainlink is the first Decentralised Oracle Network (DON), meaning that Chainlink node operators will be compensated to bring real-world data onto the blockchain. To do this, Chainlink nodes are trusted with checking up on third-party APIs and returning results for Smart Contracts deployed on public blockchains.
Chainlink DON supports two different ways of delivering off-chain data to on-chain smart contracts. The first is the Basic Request Model where smart contracts generate and submit a data request to Chainlink oracle nodes in one transaction and receive the response within a separate transaction. The second is the Decentralised Data Model, a shared data resource where Chainlink oracle nodes update with fresh data that allows smart contracts to receive data in a single transaction.