Circom vs SnarkJS

Domain-Specific Language for ZK: Provides a Rust-like syntax for writing complex arithmetic circuits with fine-grained control over constraints. This matters for protocols requiring custom, optimized logic like Aave's proof-of-reserves or Tornado Cash's anonymity pools.

Established Standard with Broad Support: The de facto circuit language with 2,800+ GitHub stars, integrated into frameworks like Hardhat and Foundry, and backed by major audits. This matters for teams prioritizing security, developer experience, and existing library support.

Pluggable Proof Systems: Supports multiple proving schemes (Groth16, PLONK) and can generate proofs from Circom, Noir, or other circuit compilers. This matters for architects who need flexibility to switch proving systems or integrate with various L1s/L2s without rewriting circuits.

Pure JavaScript Implementation: Enables proof generation and verification directly in browsers and Node.js environments. This matters for applications requiring in-browser trustless interactions, such as decentralized identity proofs or client-side transaction construction for wallets.

Requires deep cryptographic understanding: Developers must manually manage low-level constraints and wiring, increasing audit complexity and time-to-market. This is a trade-off for projects without dedicated cryptography experts, where higher-level frameworks like Noir or Cairo might be faster to prototype.

JavaScript runtime limits proving speed: Compared to native Rust provers (e.g., Arkworks, Bellman), SnarkJS proof generation can be 5-10x slower for large circuits. This is a critical trade-off for high-throughput applications like rollup sequencers where proving time directly impacts TPS and cost.

Building custom, optimized zk-circuits from scratch. Ideal for protocol teams (e.g., Aztec, Polygon zkEVM) that need maximum performance, custom gate structures, and are willing to invest in expert development and security audits.

Integrating zk-proofs into web applications or for prototyping. Perfect for dApp frontends, browser-based tools, and projects that prioritize developer accessibility and rapid iteration over ultimate proving performance.

Optimized for custom circuits: Write in a C-like language for fine-grained control over constraints and performance. This matters for high-throughput applications like rollups (e.g., Polygon zkEVM) or privacy-focused DEXs where gas efficiency is paramount.

Largest developer adoption: Backed by 5,000+ GitHub stars and integrated with major frameworks like Hardhat and Foundry via circomkit. This matters for teams needing production-ready libraries (e.g., Semaphore for identity) and extensive community support.

Requires cryptographic expertise: Developers must manually manage low-level constraints, which increases audit complexity and risk of bugs. This matters for rapid prototyping or teams without dedicated ZK specialists, as seen in early-stage protocol development.

Zero-dependency browser compatibility: Runs entirely in-browser or Node.js, enabling client-side proof generation for wallets or web apps. This matters for decentralized applications where users generate proofs locally, like anonymous voting systems.

De-facto prover for Circom circuits: Handles the entire proof lifecycle (setup, generation, verification) with a simple CLI/API. This matters for end-to-end workflow where you use Circom for design but need a robust, audited prover (used by Tornado Cash, zkSync).

JavaScript runtime limits speed: Proof generation is significantly slower (~10-100x) than native Rust/Golang provers like rapidsnark. This matters for high-frequency applications (e.g., per-block proofs) where sub-second proving is non-negotiable.