Learn ERC-8004
Long-form guides explaining the ERC-8004 standard and its on-chain registries for AI agents.
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What is ERC-8004?
ERC-8004 is the Ethereum standard for trustless AI agents. Three onchain registries — identity, reputation, and validation — give agents a portable, verifiable identity without a central registry.
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Trustless agents — what the term means and what it requires
A trustless agent is one whose identity, reputation, and behavior can be verified by anyone, onchain, without trusting a central provider. ERC-8004 is the first Ethereum standard that makes that practical.
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Onchain agents — what they are and why they matter
An onchain agent is an autonomous program whose identity, behavior history, or payments are anchored to a blockchain — so anyone can verify what it is and what it has done without trusting the platform that hosts it.
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Agent protocols — MCP, A2A, x402, AP2, and ERC-8004 explained
Five open standards together cover what an autonomous agent needs to be useful onchain — tools (MCP), peer coordination (A2A), payments (x402, AP2), and verifiable identity + reputation (ERC-8004). They are complementary, not competing.
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The three ERC-8004 registries
ERC-8004 defines three onchain registries for AI agents — identity, reputation, and validation. Each one solves a problem the others can't, and together they let an agent carry portable, verifiable history across platforms.
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ERC-8004 Identity Registry
The ERC-8004 Identity Registry mints an ERC-721 token for each AI agent. The token's tokenURI points at agent metadata, giving every agent a portable onchain identity.
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ERC-8004 Reputation Registry
The ERC-8004 Reputation Registry accepts signed feedback events from clients. Each event carries tags and a normalized rating, building a public, tamper-evident history of how an agent has actually performed.
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ERC-8004 Validation Registry
The ERC-8004 Validation Registry is a request/response market for third-party agent validation. Anyone can request a scored validation; named validators respond with a 0–100 score and optional metadata.
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ERC-8004 glossary
Definitions for 30 terms across ERC-8004 and the onchain-agent stack — identity registries, reputation, validation, and adjacent protocols (MCP, A2A, x402, AP2).