Circom

Circom is a domain-specific language and compiler designed to build arithmetic circuits for Zero-Knowledge Proofs.

Circom streamlines the creation of complex ZK circuits by abstracting low-level R1CS constraints into a modular, hardware-description style syntax. Developers use it to define signals and components that the compiler translates into efficient rank-1 constraint systems for provers like SnarkJS. It is the industry standard for production-grade applications: Tornado Cash and Semaphore both rely on Circom to manage private transactions and identity verification. By handling the heavy lifting of circuit optimization, it lets engineers focus on the logic of zero-knowledge protocols (like Merkle tree inclusion or EdDSA signatures) rather than manual constraint engineering.

https://docs.circom.io