SIWA

Sign In With Agent

Trustless identity and authentication for AI agents. An open standard built on ERC-8004.

$ npm install siwa ethers
  1. 1.Install the SDK
  2. 2.Create a wallet & register onchain
  3. 3.Authenticate with any SIWA server
Read the docs

How SIWA Works

01

Register

Agent mints an ERC-8004 identity NFT. Gets a unique agentId and agentURI pointing to its metadata.

02

Challenge

Service sends a nonce. Agent signs a structured SIWA message via the keyring proxy. Key never touches the agent.

03

Verify

Service recovers the signer, checks onchain NFT ownership, and issues a session token.

Why SIWA

Key Isolation

Private keys live in a separate keyring proxy process. Even full agent compromise cannot extract the key — only request signatures.

Onchain Identity

ERC-721 NFT on the Identity Registry. Transferable, verifiable, permanent. Your agent's identity lives onchain.

Multi-Chain

Base, Ethereum Sepolia, Linea, Polygon. Deploy on mainnet or testnets. More chains coming.

Open Standard

MIT licensed. Inspired by EIP-4361 (SIWE). Built for any agent framework — Claude, GPT, custom agents.

SIWA Message Format

Like SIWE, but extended with Agent ID and Agent Registry fields for ERC-8004 identity verification.

api.example.com wants you to sign in with your Agent account:
0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb0

Authenticate as a registered ERC-8004 agent.

URI: https://api.example.com/siwa
Version: 1
Agent ID: 42
Agent Registry: eip155:84532:0x8004A818...
Chain ID: 84532
Nonce: abc123def456
Issued At: 2026-02-05T12:00:00Z