Overview
This guide provides a comprehensive, step-by-step tutorial for integrating LayerZero V2 with the SEI blockchain. By the end of this guide, you will understand how to create, deploy, and manage omnichain tokens that can seamlessly move between SEI and any other LayerZero-supported blockchain.What This Guide Covers
- Understanding LayerZero: Core concepts and architecture
- Project Setup: Creating a LayerZero-enabled project from scratch
- Smart Contracts: Building an Omnichain Fungible Token (OFT) with detailed explanations
- Deployment & Configuration: Step-by-step deployment to SEI and other chains
- Cross-Chain Transfers: Creating tasks and scripts for token transfers
Prerequisites
- Basic knowledge of Solidity and smart contracts
- Node.js and npm installed
- A wallet with SEI and other chain tokens for gas
- Familiarity with Hardhat or Foundry
What is LayerZero?
LayerZero is an omnichain interoperability protocol that enables secure, permissionless communication between different blockchains. Think of it as a universal translator that allows blockchains to talk to each other.Core Concepts
- Endpoints: Immutable smart contracts deployed on each blockchain that serve as entry/exit points for messages
- Messages: Data packets sent between blockchains containing instructions or information
- Security Stack: Customizable verification system ensuring message authenticity
- Omnichain Applications: Smart contracts that can operate across multiple blockchains
Key Applications
- Omnichain Fungible Tokens (OFT): Tokens that exist across multiple chains with unified supply
- Omnichain NFTs (ONFT): NFTs that can move between blockchains
- Cross-chain DeFi: Protocols that operate across multiple networks
- Unified Governance: DAOs that function across chains
- Message Passing: Send arbitrary data between blockchains
SEI Network Information
- Network Name: SEI EVM
- Chain ID: 1329
- RPC URL: https://evm-rpc.sei-apis.com
- Explorer: https://seiscan.io
- Currency: SEI
- LayerZero Endpoint ID: 30280
Contract Deployments
The following are the official LayerZero V2 protocol contract addresses deployed on Sei networks.Sei Mainnet (EID: 30280) — Protocol Contracts
Sei Mainnet (EID: 30280) — Protocol Contracts
Sei Mainnet — DVNs (Decentralized Verifier Networks)
Sei Mainnet — DVNs (Decentralized Verifier Networks)
Sei Testnet (EID: 40455) — Protocol Contracts
Sei Testnet (EID: 40455) — Protocol Contracts
Step 1: Project Setup
Project scaffold
LayerZero’s CLI lets you spin up an OFT workspace in seconds:Add private keys
Rename.env.example file to .env and update it with needed configurations:
PRIVATE_KEY. RPC URLs are optional, but strongly recommended. If you don’t provide them, public RPCs will be used, but public RPCs can be unreliable or slow, leading to long waiting times for transactions to be confirmed or, at worst, cause your transactions to fail.
Step 2: Configure Networks
Hardhat network config
Update yourhardhat.config.ts file to include the networks you want to deploy your contracts to:
LayerZero wiring config
Modify yourlayerzero.config.ts file to include the chains and channel security settings you want for each connection:
Step 3: Create Utility Tasks
Before deployment, let’s create a utility task for minting tokens that we’ll need later.Create Minting Task
Createtasks/mint.ts:
Update Hardhat Configuration
Now update yourhardhat.config.ts to import the mint task:
Step 4: Smart Contract Development
The token contract
- Source Chain: Burns tokens from sender’s balance
- LayerZero Protocol: Verifies and relays the message
- Destination Chain: Mints equivalent tokens to recipient
Understanding OFT Functions
Key inherited functions from the OFT contract:Step 5: Deployment Process
Deploy
Step 6: Wire the Contracts
After deployment, contracts need to be connected:Connect the chains
Verify Configuration
Verify peers:Step 7: Mint Initial Tokens
Before transferring, you need tokens to send. Let’s mint some tokens on SEI:Step 8: Transfer Tokens Cross-Chain
Calling send
Since thesend logic has already been defined, we’ll instead view how the function should be called.
Option 1: Hardhat Task
Createtasks/sendOFT.ts:
hardhat.config.ts (if not already added):
Option 2: Foundry Script
Createscript/SendOFT.s.sol:
Step 9: Done!
You’ve issued an omnichain token and bridged it from Sei Mainnet to Optimism. Customize supply logic, fees, or add more chains by applying changes to the core contract, redeploying, and repeating the wiring step.Track Your Transaction
- Visit https://layerzeroscan.com/tx/YOUR_TX_HASH
- You’ll see:
- Source transaction
- Message status
- Destination transaction
- Time elapsed
- Check balances on both chains to confirm the transfer
Troubleshooting
Common Issues and Solutions
quoteSend call reverts, it usually means that your LayerZero wiring hasn’t been fully configured or there’s no default pathway for the chains you’re trying to bridge. Here’s how to diagnose and fix it:1. Wiring Didn’t Succeed:Run the following to inspect your on‑chain wiring configuration:LzDeadDVN. Those entries indicate that a default pathway setting does not exist.- Check: You can see if your configuration contains a LzDeadDVN by viewing the Default Config Checker on LayerZero Scan.
-
Fix: Open your
layerzero.config.tsand under the relevantpathwaysentry, add working DVN providers (in the[ requiredDVN[], [ optionalDVN[], threshold ] ]section). - Re-run your wiring command for the connections so that the wiring on both chains is live.
quoteSend flow. It should now return a fee estimate instead of reverting.Next Steps
- Add More Chains: Expand to Arbitrum, Base, Polygon, etc.
- Advanced Features: Implement rate limiting, pausable transfers, fee collection
- Composed Messages: Execute actions after token arrival
- Build a UI: Create a frontend for easy transfers
Learn More
- See the Configuring Pathways section to learn more about managing your OFTs across the entire network mesh.
- See the Available DVNs and Executor to configure between.
- Learn how the protocol works by reading the Core Concepts section.
- Learn more about how the OFT contract works on the EVM by reading the OFT Quickstart in the EVM section.
Resources
- LayerZero Documentation: https://docs.layerzero.network/v2
- LayerZero Scan: https://layerzeroscan.com/
- SEI Explorer: https://seiscan.io
Summary
You’ve successfully:- ✅ Created an Omnichain Fungible Token project
- ✅ Configured networks and LayerZero pathways
- ✅ Deployed contracts to multiple chains
- ✅ Connected the deployments via LayerZero wiring
- ✅ Created tasks for cross-chain token transfers
- ✅ Learned how LayerZero enables omnichain applications