@web3auth/sign-in-with-web3

Authenticate users with their Web3 accounts instead of relying on custodial OAuth providers. Users sign a standard message with any Web3-compatible wallet, keeping full control of their identity and data.

Sign-In with Web3 uses a standard message format compliant with CAIP-74, parameterized by scope, session details, and security mechanisms (e.g., a nonce).

Supported Chains

• Ethereum — EIP-4361 with EIP-1271/6492 smart contract signature support
• Solana — SIP-99 with ed25519 signature verification

Installation

npm install @web3auth/sign-in-with-web3

Usage

Register strategies

Strategies are not auto-registered. Register the chains you need before using SIWWeb3:

import { SIWWeb3, ethereumStrategy, solanaStrategy } from "@web3auth/sign-in-with-web3";

SIWWeb3.registerStrategy(ethereumStrategy);
SIWWeb3.registerStrategy(solanaStrategy);

Basic

// Parse a signed message string (chain is detected automatically)
const msg = new SIWWeb3(messageString);

// Or construct from fields (chain is required)
const msg = new SIWWeb3({
  chain: "ethereum", // or "solana"
  payload: {
    domain: "example.com",
    address: "0x...",
    statement: "Sign in with Ethereum to the app.",
    uri: "https://example.com",
    version: "1",
    chainId: 1,
    nonce: "32891757",
    issuedAt: new Date().toISOString(),
  },
});

// Generate the EIP-4361 message to sign
const messageToSign = msg.prepareMessage();

// Verify a signature
const { success, error } = await msg.verify(msg.payload, signature);

Using chain-specific classes directly

import { SIWE, SIWS } from "@web3auth/sign-in-with-web3";

const ethMsg = new SIWE({ header, payload, signature });
const solMsg = new SIWS(messageString);

Registering a custom strategy

import { SIWWeb3 } from "@web3auth/sign-in-with-web3";

SIWWeb3.registerStrategy({
  chain: "mychain",
  parse: (msg) => new MyChainSIW(msg),
  create: (params) => new MyChainSIW(params),
});

Architecture

src/
  client.ts          — SIWWeb3 (main entry, strategy registry)
  strategies/
    base.ts          — SIWBase (abstract base class)
    ethereum.ts      — SIWE + EIP-1271/6492 verifier
    solana.ts        — SIWS + ed25519 verifier
  regex.ts           — Shared message parsing
  types.ts           — Shared types

Exports

Export	Description
SIWWeb3	Main class with chain auto-detection and strategy registry
SIWBase	Abstract base class for building custom chain strategies
SIWE	Ethereum sign-in (EIP-4361)
SIWS	Solana sign-in (SIP-99)
ethereumStrategy	Ethereum strategy for registry
solanaStrategy	Solana strategy for registry
eipVerifyMessage	EIP-1271/6492 signature verification utility

Migration from @web3auth/sign-in-with-ethereum / @web3auth/sign-in-with-solana

These packages have been deprecated and consolidated into this package.

- import { SIWEthereum } from "@web3auth/sign-in-with-ethereum";
- import { SIWS } from "@web3auth/sign-in-with-solana";
+ import { SIWWeb3, ethereumStrategy, solanaStrategy, SIWE, SIWS } from "@web3auth/sign-in-with-web3";
+ SIWWeb3.registerStrategy(ethereumStrategy);
+ SIWWeb3.registerStrategy(solanaStrategy);

Key changes from previous versions:

• SIWEthereum has been renamed to SIWE
• network property has been renamed to chain
• chain is now required when constructing from an object
• Strategies must be registered manually (no longer auto-registered)

Docs