SpruceID Sign-in with Ethereum (SIWE) vs SBT-based Authentication

Session-based authentication: Uses a signed message (EIP-4361) to prove wallet ownership for a single session. This is ideal for low-friction web2-style logins where you just need to verify 'who is this user right now?' without on-chain state changes. It's the standard for dApps like OpenSea and Mirror.xyz.

Stateful credential tokens: Soulbound Tokens (ERC-721, ERC-1155, ERC-5192) are non-transferable NFTs that live in a user's wallet, representing persistent attributes (e.g., KYC status, guild membership). This is critical for reputation systems, gated access, and sybil resistance where credentials must be verifiable across multiple sessions and applications.

Gasless for users: Authentication happens via a signature, not a transaction. No gas fees for login. Simpler integration: Relies on established wallet providers (MetaMask, WalletConnect) and libraries like @spruceid/siwe. Lower overhead for projects that don't need persistent on-chain identity states.

On-chain verifiability: Credentials are publicly queryable by any smart contract or indexer, enabling complex logic (e.g., 'only users with X SBT and Y token balance'). Ecosystem composability: SBTs issued by protocols like Guild.xyz or Orange Protocol can be used across the entire dApp ecosystem, creating a portable identity layer.

Standardized Simplicity & Interoperability: Built on EIP-4361, SIWE provides a universal login flow for any EVM wallet (MetaMask, Coinbase Wallet). This matters for user onboarding as it reduces integration complexity and leverages a massive existing user base, avoiding the need for new credential issuance systems.

Ephemeral Session Context: Authentication is tied to a wallet signature for a single session. This matters for persistent, portable identity because it cannot natively carry verified claims (like KYC status or reputation) across different applications without repeated off-chain verification.

Persistent, Verifiable Credentials: Soulbound Tokens (SBTs) are non-transferable NFTs that act as on-chain attestations (e.g., proof-of-humanity, guild membership). This matters for reputation-based systems and sybil resistance because credentials are publicly verifiable and travel with the user's wallet across the ecosystem.

Ecosystem Fragmentation & Complexity: No single SBT standard dominates (competing with EIP-4973, ERC-721, etc.), and issuers (like Gitcoin Passport, Orange Protocol) are siloed. This matters for developer adoption as it requires integrating multiple issuance protocols and managing complex revocation logic, increasing overhead.

Simple Web2-Like Login Flows where you need frictionless onboarding for a broad audience. Ideal for:

• NFT marketplaces (OpenSea, Blur)
• DeFi dashboards (Aave, Uniswap)
• Content gating where session-based access is sufficient.

Trust-Minimized, Reputation-Based Systems requiring persistent, composable identity. Ideal for:

• DAO governance with voting power based on credentials (e.g., Optimism's Citizen House)
• Under-collateralized lending (e.g., Arcx)
• Sybil-resistant airdrops and community access.

Persistent on-chain reputation: Auth sessions can be enriched with a user's immutable history of SBTs, enabling reputation-based experiences. A protocol like Lens Protocol uses this for social graphs. This matters for credit scoring, governance power, or personalized UX where past actions determine future access.

Limited to wallet possession: Proves key ownership, but not identity attributes. Requires off-chain services (like Ceramic or Verite) to layer on credentials, adding complexity. Not ideal for role-based access control (RBAC) where user traits, not just a key, must be evaluated.

Higher cost and latency: Minting and verifying on-chain SBTs incur gas fees and block time delays. Immature tooling: Standards (ERC-5114, ERC-4973) are emerging, but wallet support and developer SDKs are less mature than SIWE. This adds significant engineering overhead for production systems.