Chainlink (chainlink)

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What it offers

• getLatestPrice: Read latest price from a Chainlink price feed aggregator

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Notes

• Price feeds return answer in int256 with feed-specific decimals (usually 8 for USD pairs)
• Always check updatedAt timestamp for staleness - stale prices can cause issues
• Feed Registry is Ethereum-only; on L2s, use individual feed addresses directly
• VRF provides verifiable randomness for on-chain applications
• Common feed addresses vary by chain - check Chainlink docs for specific chain deployments

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Its names in a program

function main() {
  // Ethereum's ethUsdFeed, `0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419`.
  require(Chainlink.EthUsdFeed != 0);
}

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Deployments

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ABI

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AggregatorV3ABI

• latestRoundData() view returns (uint80 roundId, int256 answer, uint256 startedAt, uint256 updatedAt, uint80 answeredInRound)
• decimals() view returns (uint8)

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FeedRegistryABI

• latestRoundData(address base, address quote) view returns (uint80 roundId, int256 answer, uint256 startedAt, uint256 updatedAt, uint80 answeredInRound)
• getFeed(address base, address quote) view returns (address aggregator)

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Next steps

• Protocols: the other protocols, by what they do.
• Protocols and tokens: calling a contract by its namespace, or through its ABI.
• Glossary: the words these pages use, in plain terms.