what's Malachite?

Malachite is a high-performance, flexible Byzantine Fault Tolerant (BFT) consensus engine implemented in Rust. Originally developed by Informal Systems, it supports customizable consensus mechanisms suitable for blockchain networks requiring robustness and scalability. In August 2025, Circle acquired Malachite to serve as the core consensus layer for its upcoming Arc blockchain, designed specifically for stablecoin-based financial applications. Variants like Malaketh enable integration with Ethereum execution clients via the Engine API, demonstrating adaptability for L1 blockchains and L2 sequencers.

Malachite is Circle's Arc consensus variant, immune to CometBFT's block time manipulation flaw.