Citrea is a Bitcoin-native Layer 2 project designed to scale Bitcoin using zero-knowledge (ZK) rollup technology. Unlike traditional Bitcoin sidechains that rely on external validators or multisig bridges, Citrea uses Bitcoin itself as the settlement and data availability layer, allowing transactions to inherit Bitcoin’s security and decentralization. The project aims to expand Bitcoin’s utility beyond simple payments by enabling smart contracts, DeFi, and other programmable applications directly secured by the Bitcoin network.

Citrea is built as a Type-2 zkEVM, meaning Ethereum developers can deploy Solidity-based applications with minimal modifications while still leveraging Bitcoin as the underlying security layer. The network batches transactions off-chain, generates zero-knowledge proofs, and submits those proofs back to Bitcoin for verification. Through technologies such as BitVM and its trust-minimized bridge system called Clementine, Citrea seeks to provide scalable BTCFi infrastructure without requiring changes to Bitcoin’s consensus rules.

The broader vision of Citrea is to transform Bitcoin into a fully programmable financial ecosystem while preserving the core principles that made Bitcoin valuable: censorship resistance, decentralization, and security. By combining Bitcoin settlement with EVM compatibility, Citrea aims to unlock applications such as decentralized exchanges, lending protocols, stablecoins, and on-chain financial services for Bitcoin users. The project is often positioned as one of the leading attempts to bring Ethereum-like programmability and scalability to the Bitcoin ecosystem through ZK technology.