EAS (Ethereum Attestation Service)

by EAS (open source) · attest.org

Identity Open Source

Best for: Building agent reputation systems; issuing verifiable credentials on-chain; trust scores

Not ideal for: Off-chain identity; non-EVM chains; simple name resolution

Key Signals

Mechanism

On-chain attestations

Chains

EVM (10+ chains)

Integration

SDK

Pricing

Free (gas only)

Features

📜

Schema-Based Attestations

Define custom schemas for any type of claim: "this agent completed a task successfully", "this agent passed safety review", "this agent's operator is KYC-verified". Schemas are registered on-chain and reusable by anyone.

⚙️

On-chain and Off-chain Modes

Attestations can be stored fully on-chain (highest trust, costs gas) or off-chain (free, stored in IPFS or other systems with a signed hash anchored on-chain). Off-chain mode makes EAS practical for high-volume reputation systems.

🌱

Composable Reputation

Attestations from multiple issuers can be aggregated to build composite reputation scores. An agent can hold attestations from its operator, from users it has served, from auditors who reviewed its code, and from platforms it has integrated with.

🆓

Free to Use

EAS contracts are free to call — you only pay the network gas fee. Deployed on Ethereum, Base, Optimism, Arbitrum, Polygon, Scroll, and more. For high-volume use cases, L2 deployment keeps attestation costs negligible.

Ratings

Flexibility

4.8

Decentralization

4.7

Ecosystem Maturity

4.0

Ease of Setup

4.2

Ratings based on documentation review, GitHub activity, and public developer reports. Not independently verified in production.

Integration

npm install @ethereum-attestation-service/eas-sdk

import { EAS, SchemaEncoder } from '@ethereum-attestation-service/eas-sdk';
import { ethers } from 'ethers';

const EAS_CONTRACT = '0x4200000000000000000000000000000000000021'; // Base
const eas = new EAS(EAS_CONTRACT);

const provider = new ethers.JsonRpcProvider('https://mainnet.base.org');
const signer   = new ethers.Wallet(process.env.PRIVATE_KEY, provider);
eas.connect(signer);

// Register a schema: "agent task completion"
const SCHEMA_UID = '0xYOUR_SCHEMA_UID'; // registered via SchemaRegistry

const schemaEncoder = new SchemaEncoder(
  'address agentAddress, string taskId, bool success, uint8 qualityScore'
);

const encoded = schemaEncoder.encodeData([
  { name: 'agentAddress', value: '0xAGENT_ADDRESS', type: 'address' },
  { name: 'taskId',       value: 'task-42',         type: 'string'  },
  { name: 'success',      value: true,              type: 'bool'    },
  { name: 'qualityScore', value: 95,                type: 'uint8'   },
]);

const tx = await eas.attest({
  schema: SCHEMA_UID,
  data: { recipient: '0xAGENT_ADDRESS', expirationTime: 0n, revocable: true, data: encoded },
});

const attestationUID = await tx.wait();
console.log('Attestation UID:', attestationUID);
        

Alternatives

Coinbase Verifications

KYC-backed attestations — pre-built schemas for verified identity backed by Coinbase KYC

→

Spectral

Credit scoring — ML-based on-chain credit scores as an alternative reputation mechanism

→

World ID

Proof-of-personhood — single attestation proving a unique human operator, not a reputation system

→