Aztec vs. StarkEx (Privacy Modes)

Privacy as default: Aztec's zk-zkRollup architecture (using PLONK) enables private smart contract execution and private state by default. This matters for applications requiring end-to-end confidentiality, like private DeFi (zk.money) or confidential voting.

Higher development overhead: Building on Noir (Aztec's custom ZK language) and managing private state is more complex than standard Solidity. The ecosystem of tools (Noir-VSCode, Aztec Sandbox) is growing but less mature. This matters for teams with tight timelines or those prioritizing developer familiarity.

Proven scalability for specific apps: StarkEx's Validium/Volition model (using STARKs) offers ~9,000 TPS for applications like dYdX (perpetuals) and Immutable X (NFTs). This matters for high-volume, low-latency exchanges and gaming platforms where public data availability is acceptable.

Privacy is an opt-in feature: StarkEx is an application-specific rollup. While it offers "privacy pools" (via Volition), privacy is not the default state of the system. This matters for projects that need granular, user-controlled privacy rather than a fully private L2 environment.

Universal privacy for any dApp logic: Developers can build private DeFi, voting, or identity apps using Noir, a Rust-like ZK-SNARK language. This enables custom private smart contracts, unlike StarkEx's fixed application modes. This matters for protocols requiring novel, complex private logic (e.g., private DAOs, confidential auctions).

Base-layer privacy for ETH and ERC-20s: Aztec's architecture anonymizes sender, receiver, and amount by default using ZK-SNARKs. This provides stronger privacy guarantees than mixing solutions. This matters for users and institutions requiring maximal transaction confidentiality, similar to Zcash on Ethereum.

Proven scalability for specific applications: StarkEx powers dYdX (perpetuals) and Immutable X (NFTs), handling 9,000+ TPS in production. Fees are lower due to STARK proofs and application-specific optimization. This matters for exchanges, gaming, and NFT platforms where cost and speed are critical.

Production-ready with significant TVL: StarkEx has secured >$1T+ in cumulative trading volume with zero security breaches. Its Validium and Volition modes let users choose data availability. This matters for enterprises and large protocols that prioritize security audits, institutional trust, and regulatory clarity.

ZK-SNARK proof generation is user-side: Users must generate proofs locally, leading to higher gas fees and slower UX (~30-45 sec proof time). This creates friction for mainstream adoption. This is a critical consideration for consumer apps where speed and low cost are paramount.

Privacy is application-specific, not universal: StarkEx offers "selective privacy" modes (e.g., spot trading, NFTs) but not a general-purpose private VM. Building novel private logic requires a custom circuit, which is complex. This matters for developers wanting the flexibility of Ethereum's composability but with privacy.

Universal privacy: Every transaction is private by default using zero-knowledge proofs (ZKPs). This matters for applications requiring complete data confidentiality, like private DeFi (zk.money) or enterprise payroll. The network is purpose-built for privacy-first use cases.

Custom private logic: Developers use the Noir language to write private smart contracts. This matters for building bespoke private applications (e.g., private voting, confidential auctions) that require complex, user-defined logic within a privacy-preserving environment.

Scalability-first: Leverages STARK validity proofs for massive throughput (e.g., dYdX processed ~10K TPS). This matters for high-frequency trading platforms and NFT marketplaces where performance and cost are primary, and privacy is an optional feature ("Validium" mode).

Proven in production: Powers major live applications like Immutable X, Sorare, and dYdX with over $1T+ in cumulative volume. This matters for enterprise-grade deployments requiring a stable, audited stack with existing L1 security (via Data Availability Committees or Ethereum).

ZK-proof overhead: Every private action requires generating a client-side ZK proof, leading to slower UX and higher gas costs per transaction. This is a trade-off for universal privacy, making it less ideal for micro-transactions or latency-sensitive dApps.

Privacy as a feature, not foundation: Privacy modes ("ZK-Rollup" for full, "Validium" for partial) are application-level choices with trust assumptions (e.g., Data Availability Committee). This matters if you need guaranteed cryptographic privacy for all data, which Validium mode does not provide.