LayerZero

LayerZero V2 is an immutable, censorship-resistant messaging protocol for cross-chain communication. It enables smart contracts on different blockchains to send arbitrary messages to each other through a modular security stack of Decentralized Verifier Networks (DVNs). The core primitive is the OApp (Omnichain Application) — a contract that inherits OApp.sol and implements _lzSend / _lzReceive to send and receive cross-chain messages through EndpointV2.

What You Probably Got Wrong

AI agents trained before mid-2024 confuse V1 and V2 architecture. These are the critical corrections.

• V2 is NOT V1 — completely different architecture. V1 used LZApp, ILayerZeroEndpoint, and a monolithic oracle+relayer model. V2 uses OApp, EndpointV2, and modular DVNs+Executors. Do NOT import @layerzerolabs/solidity-examples — that is V1. Use @layerzerolabs/oapp-evm for V2.
• OFT burns on source, mints on destination — NOT a lock/mint bridge. The Omnichain Fungible Token standard burns tokens on the source chain and mints equivalent tokens on the destination. For existing ERC-20s that cannot add burn/mint, use OFTAdapter which locks on source and mints an OFT representation on destination.
• DVNs replace the V1 oracle+relayer model. V1 had a single Oracle and Relayer operated by LayerZero Labs. V2 decouples verification into configurable DVN sets — you choose which DVNs must verify your messages and set quorum thresholds.
• _lzSend requires proper fee estimation via quoteSend() or _quote(). You must call the quote function first to determine the exact MessagingFee (native + lzToken), then pass that fee as msg.value. Underpaying reverts.
• Peer addresses must be set on BOTH chains. Calling setPeer(dstEid, bytes32(peerAddress)) on chain A is not enough. You must also call setPeer(srcEid, bytes32(chainAAddress)) on chain B. Unset peers cause NoPeer reverts.
• Message ordering is NOT guaranteed unless you configure ordered delivery. V2 delivers messages in a nonce-based system, but by default the executor can deliver messages out of order. Use the OrderedNonce enforcement option if strict ordering matters.
• eid (Endpoint ID) is NOT the chain ID. LayerZero uses its own Endpoint ID system. Ethereum mainnet is eid 30101, Arbitrum is 30110, Base is 30184, Optimism is 30111, Polygon is 30109. Using chain IDs instead of eids is the most common integration mistake.
• Peer addresses are bytes32, not address. All peer addresses are stored as bytes32 to support non-EVM chains. For EVM addresses, left-pad with zeros: bytes32(uint256(uint160(addr))). Passing a raw address to setPeer will fail.
• The Executor is separate from DVNs. DVNs verify messages, but the Executor actually calls lzReceive on the destination. You can configure a custom Executor or use the LayerZero default. If you set gas limits too low in message options, the Executor will run out of gas on the destination.

Quick Start