Union is a trust-minimized, zero-knowledge bridging protocol built in Rust that enables censorship-resistant cross-chain communication and asset transfers for decentralized finance applications. The protocol implements consensus verification without reliance on trusted third parties, oracles, multi-signatures, or MPC, distinguishing it from conventional bridging solutions. Union integrates with Cosmos chains through IBC compatibility and connects to EVM chains including Ethereum, Arbitrum, Base, Berachain, and numerous others, supporting both mainnet and testnet deployments across a diverse ecosystem of blockchain networks.
The repository contains multiple specialized components working in concert to deliver the protocol's functionality. The uniond component serves as the Union node implementation using CometBLS, while galoisd provides the zero-knowledge prover implementation. Voyager functions as a modular, high-performance cross-ecosystem relayer written in Rust. The cosmwasm directory contains the CosmWasm smart contract stack with light clients for various ecosystems, and the evm directory houses Solidity-based smart contracts for EVM compatibility. Supporting infrastructure includes unionvisor, a production-grade node supervisor, drip, a faucet for Cosmos chains, and a TypeScript SDK for programmatic interaction with Union.
The project maintains a web presence through multiple components: app.union.build provides a user-facing application built with TypeScript and Svelte, while union.build serves as the main website constructed with TypeScript and Astro. Development is facilitated through Nix, enabling reproducible builds across all components and providing a comprehensive development shell with all necessary dependencies including Cargo, Rustc, Node, and Go. The repository explicitly supports macOS developers using OrbStack for NixOS virtualization, reflecting practical consideration for the development community.
Activity tracking reveals sustained engagement with the codebase.
The protocol's governance model ensures decentralized control over contract upgradability, connections, token configurations, and protocol evolution. This alignment of Union's priorities with users, validators, and operators reflects a commitment to community-driven development. The supported chain list encompasses major networks like Ethereum, Arbitrum, and Osmosis alongside emerging ecosystems such as Berachain and Babylon, with testnet availability enabling developer experimentation.
