Develop an Oracle

Get paid to perform one of the roles in the LayerZero system.

Oracle Specification

Performing the job of an Oracle means moving a piece of the message data from one chain and storing it in another. Please refer to our Oracle Specification document to learn more.
Two of the primary requirements for operating an Oracle (per-chain):
  • Deploy and maintain balances in your own contract.
  • Implement and operate a system that can submit data from Chain A to Chain B.
In this gitbook, we wont get into the details of the implementation of an Oracle because the LayerZero relies on other ecosystem parters. We do however expose some example solidity contracts to demonstrate the contractual portion of a simple Oracle on an EVM:
  • Heres the Oracle we use for internal testing:
// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.7.6;
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "../interfaces/ILayerZeroOracle.sol";
import "../interfaces/ILayerZeroUltraLightNodeV1.sol";
contract LayerZeroOracleMock is ILayerZeroOracle, Ownable, ReentrancyGuard {
mapping(address => bool) public approvedAddresses;
mapping(uint16 => mapping(uint16 => uint)) public chainPriceLookup;
uint public fee;
ILayerZeroUltraLightNodeV1 public uln; // ultraLightNode instance
event OracleNotified(uint16 dstChainId, uint16 _outboundProofType, uint blockConfirmations);
event Withdraw(address to, uint amount);
constructor() {
approvedAddresses[msg.sender] = true;
function notifyOracle(uint16 _dstChainId, uint16 _outboundProofType, uint64 _outboundBlockConfirmations) external override {
emit OracleNotified(_dstChainId, _outboundProofType, _outboundBlockConfirmations);
function updateHash(uint16 _remoteChainId, bytes32 _blockHash, uint _confirmations, bytes32 _data) external {
require(approvedAddresses[msg.sender], "LayerZeroOracleMock: caller must be approved");
uln.updateHash(_remoteChainId, _blockHash, _confirmations, _data);
function withdraw(address payable _to, uint _amount) public onlyOwner nonReentrant {
(bool success, ) ={value: _amount}("");
require(success, "failed to withdraw");
emit Withdraw(_to, _amount);
// owner can set uln
function setUln(address ulnAddress) external onlyOwner {
uln = ILayerZeroUltraLightNodeV1(ulnAddress);
// mock, doesnt do anything
function setJob(uint16 _chain, address _oracle, bytes32 _id, uint _fee) public onlyOwner {}
function setDeliveryAddress(uint16 _dstChainId, address _deliveryAddress) public onlyOwner {}
function setPrice(uint16 _destinationChainId, uint16 _outboundProofType, uint _price) external onlyOwner {
chainPriceLookup[_outboundProofType][_destinationChainId] = _price;
function setApprovedAddress(address _oracleAddress, bool _approve) external {
approvedAddresses[_oracleAddress] = _approve;
function isApproved(address _relayerAddress) public view override returns (bool) {
return approvedAddresses[_relayerAddress];
function getPrice(uint16 _destinationChainId, uint16 _outboundProofType) external view override returns (uint) {
return chainPriceLookup[_outboundProofType][_destinationChainId];
fallback() external payable {}
receive() external payable {}