zkPass vs Sismo: The Architecture of Trust

zkPass excels at privacy-preserving verification of off-chain data because it leverages zero-knowledge proofs (ZKPs) to cryptographically prove statements about data from any HTTPS website without revealing the raw data itself. For example, a user can prove they are over 18 from a government ID portal or prove a bank account balance exceeds $10K, enabling compliant DeFi access while keeping the exact figure secret. This makes it a powerful tool for bridging Web2 data silos to Web3 applications.

Sismo takes a different approach by focusing on on-chain reputation aggregation and attestation. Its strategy is built around non-transferable Soulbound Tokens (SBTs) called "Badges," which are minted based on proofs of existing on-chain or off-chain affiliations. This results in a trade-off: while less focused on proving arbitrary off-web data, it creates a portable, composable social graph. Sismo's architecture is optimized for sybil resistance and community building, as seen in its integration with protocols like Lens Protocol and Aave for governance.

The key trade-off: If your priority is KYC/AML compliance, creditworthiness checks, or verifying specific data points from traditional web sources, choose zkPass. Its TransGate protocol is designed for high-stakes, granular data verification. If you prioritize building sybil-resistant communities, aggregating on-chain reputation, or enabling governance based on proven affiliations, choose Sismo. Its Badge system creates a persistent, user-controlled identity layer that other dApps can freely build upon.

zkPass excels at privacy-preserving verification of real-world data because its core technology, the TransGate Protocol, enables users to prove statements about data from any HTTPS website without revealing the underlying documents. For example, a DeFi protocol could verify a user's credit score from a traditional financial institution or their KYC status from a government portal, enabling compliant, on-chain underwriting while keeping the raw PDFs private. This bridges Web2 and Web3 data silos with cryptographic guarantees.

Sismo takes a different approach by focusing on on-chain reputation aggregation and attestation. Its strategy is built around ZK Badges—non-transferable, private attestations derived from a user's existing Web2 (e.g., Twitter, GitHub) and Web3 (e.g., POAPs, DAO voting history) footprints. This results in a trade-off: while it doesn't natively verify arbitrary off-chain documents, it is exceptionally efficient for building sybil-resistant communities and curating granular, portable reputation graphs from verifiable on-chain activity.

The key architectural trade-off is source data flexibility versus on-chain composability. zkPass provides a universal adapter for any HTTPS-accessible data source, a critical advantage for applications requiring real-world compliance, creditworthiness, or institutional data. Sismo's model is optimized for sybil resistance, governance, and social curation within the existing Web3 ecosystem, where its badges become powerful, private primitives for protocols like Lens or DAO tooling.

Consider zkPass if your priority is integrating verifiable credentials from traditional systems (financial, legal, governmental) to enable novel on-chain products like private credit scoring or compliant access gates. Its value is highest when the required proof must come from a specific, authoritative off-chain source.

Choose Sismo when your primary need is to leverage a user's aggregated digital identity—their combined history across social media, NFTs, and DAOs—to create permissioned experiences, distribute airdrops, or manage governance rights. It is the superior tool for building within the native Web3 social and governance stack.