How to add Sign in With Ethereum (SIWE) to your EVM app

Sign-In with Ethereum (SIWE), defined in EIP-4361, allows for seamless logins for Ethereum ecosystem apps. Users sign a message with their private key; your backend verifies the signature. No password database, no centralized identity provider, no extra steps. Simply EVM-native onboarding.

This guide covers why SIWE is worth adding, who it's right for, and how to integrate it using Reown.

Why Add Sign-In with Ethereum (SIWE) to Your App?

Before you get started with implementing an authentication solution, let's get into why EVM native auth might suit your blockchain app.

Tap into the existing Ethereum user base

SIWE is the established authentication standard across the EVM ecosystem. Any user with an Ethereum-compatible wallet can sign in to your app immediately, without creating a new account or going through an onboarding flow they haven't seen before. Reown connects to 500+ wallets, so you're not limiting users to a specific provider.

Give users control over their identity

Traditional Web3 login often locks users into a specific wallet or platform. SIWE is wallet-agnostic — users authenticate with whatever wallet they already trust, and your app treats the verified address as their identity. No custodial accounts, no platform dependency.

Reduce authentication to a single action

Standard Web3 login involves two separate steps: connecting a wallet, then signing a message. SIWE combines both into a single user gesture. The connection and signature happen simultaneously, which meaningfully reduces the drop-off that happens when users are asked to approve multiple prompts before they've done anything in your app.

However, if you need authentication across non-EVM chains like Solana or Bitcoin, Reown also supports Multichain Auth (SIWX) — the natural evolution of SIWE that is more chain agnostic.

Who Should Add Sign-In with Ethereum (SIWE) to Their Apps?

DeFi apps

DeFi users are already managing their own keys and expect non-custodial authentication as the baseline. SIWE provides cryptographically verified identity without compromising asset custody — no centralized login means no centralized point of failure. Read more about building DeFi apps with Reown.

Onchain marketplaces

Marketplaces need users to verify wallet ownership before they can list, bid, or purchase. SIWE handles that verification in a single click, bridging the gap between a wallet address and a personalised session without requiring users to register separately. Read more about building marketplaces with Reown.

Governance platforms

Governance participation requires high-integrity verification — votes need to be traceable to a specific wallet address. SIWE provides that authentication layer without adding friction. Governance drop-off is often a UX problem: the more steps between a user and their vote, the fewer votes get cast. SIWE removes a meaningful barrier.

How Does Sign-In with Ethereum (SIWE) Work?

When a user initiates sign-in, the Reown SDK generates a SIWE message conforming to the EIP-4361 standard. This message includes the app's domain, the user's Ethereum address, a nonce to prevent replay attacks, and a timestamp.

The SDK then prompts the user's wallet to sign the message — this is the single user action. The wallet signs without broadcasting a transaction, so there's no gas cost. Your backend receives the signed message, verifies the signature against the stated address, and establishes a session tied to that wallet.

The result: your app knows exactly which wallet address is authenticated, you can associate session data and preferences with that address, and the user never created a password.

Want to try out the flow for yourself? Check it out SIWE in the Reown demo ->

What to Consider When Adding Sign-In with Ethereum (SIWE)

User experience

SIWE is optimised for Ethereum-native users who are already comfortable connecting wallets. SIWE's single-prompt flow — where connect and sign happen together — is significantly smoother than the two-step flow users are used to. That said, if a meaningful portion of your audience is new to Web3 entirely, pairing SIWE with social and email login options gives those users an alternative entry point.

Regulation and compliance

Standard SIWE verifies wallet ownership but doesn't perform identity verification. If your app is subject to regulatory requirements — such as the Travel Rule or KYC obligations — SIWE alone won't be sufficient. In those cases, Multichain Auth (SIWX) integrates with verification APIs to layer compliance on top of authentication without breaking the user experience.

Security

SIWE messages are signed off-chain and never broadcast to the blockchain. The nonce in each message prevents replay attacks, and signature verification ties the session to a specific address. Private keys never leave the user's wallet. The main risk vector is frontend phishing — users signing messages on malicious sites — which is mitigated by displaying the domain clearly in the SIWE message and using a consistent, recognisable UI.

Chain support

SIWE covers EVM-compatible chains only. If your roadmap includes Solana, Bitcoin, or other non-EVM networks, SIWX provides the same message-based authentication model extended to those ecosystems. You can start with SIWE and migrate to SIWX without restructuring your authentication flow.

Before You Add Sign-In with Ethereum (SIWE)

1. Set up a project on the Reown Dashboard

You'll need a Project ID to initialise the Reown SDK. Sign in at dashboard.reown.com, create a new project, and copy the Project ID.

2. Install the Reown SDK

Add the Reown SDK to your project for your chosen framework. The SIWE authentication docs include framework-specific installation steps for React, Next.js, Vue, and others.

3. Prepare a backend verification endpoint

SIWE requires server-side signature verification. You'll need an endpoint that receives the signed message and address, verifies the signature, and returns a session. The docs include reference implementations for common backend setups.

How to Integrate Sign-In with Ethereum (SIWE): A Step-by-Step Guide

Step 1: Initialise the Reown SDK with your Project ID

Set up the Reown SDK in your project by providing your Project ID and app metadata. This configures the environment and enables wallet connectivity across 500+ supported wallets. Full initialisation code for each supported framework is in the SIWE docs.

Step 2: Configure your SIWE provider

Define your SIWE configuration: the app domain, a function to generate the EIP-4361 message, and the backend endpoint that handles signature verification. The message generation function receives the wallet address and chain ID; the verification function receives the signed message and returns the authenticated session.

Step 3: Connect the sign-in trigger in your UI

Add the Reown connection component to your app's UI. When the user clicks to sign in and selects their wallet, the SDK handles the SIWE flow automatically — connecting the wallet and requesting the signature in a single step. Your backend verification endpoint receives the signature and issues the session.

Check out the full SIWE implementation info in the Reown docs ->

Why Reown for Sign-In with Ethereum (SIWE)?

500+ wallet connections, one integration

Reown's SDK handles connectivity across the entire EVM wallet landscape. You configure SIWE once; users can sign in with MetaMask, Rabby, Coinbase Wallet, or any of 500+ other wallets without additional integration work on your end.

Built-in analytics

The Reown Dashboard surfaces authentication data automatically; connection methods, wallet distribution, session volume, drop-off rates. You can see exactly where users are abandoning the authentication flow and act on it, without separate analytics tooling.

To learn more, check out the Reown Analytics overview in the docs ->

A clear upgrade path to multichain

If your app grows beyond EVM, SIWX extends the same authentication model to Solana, Bitcoin, and other chains using the same SDK. You're not locked into EVM-only authentication; the Reown SDK is built to scale with your chain support.

Conclusion: Add SIWE and Remove the Authentication Barrier

SIWE is the right authentication choice for EVM-focused apps that want to offer users a secure, self-custodial login without the friction of a two-step connect-and-sign flow. One integration gives you wallet-verified identity, session management, and a smooth path to multichain authentication when you need it.

Get started at dashboard.reown.com, or go straight to the SIWE docs to start building.

For a broader view of what Reown's authentication layer supports, visit reown.com/solutions/authentication.