Smart Contract Deployment to Polygon

Deploying Smart Contracts to Polygon

Polygon PoS is not a separate L1, but a sidechain with its own validators that uses Ethereum as a checkpoint layer. From a developer's perspective: full EVM compatibility, MATIC as gas token, block time around 2 seconds, gas 10-100 times cheaper than Ethereum mainnet. Deploying a contract written for Ethereum to Polygon takes minutes.

Deployment Preparation

Network Configuration

Polygon has two public RPCs:

• Official: https://polygon-rpc.com (often overloaded)
• Recommended: Alchemy/Infura/QuickNode endpoints (more reliable)

In hardhat.config.ts:

import { HardhatUserConfig } from "hardhat/config"

const config: HardhatUserConfig = {
  networks: {
    polygon: {
      url: process.env.POLYGON_RPC_URL || "https://polygon-rpc.com",
      accounts: [process.env.DEPLOYER_PRIVATE_KEY!],
      gasPrice: "auto",  // or fixed value in gwei
      chainId: 137
    },
    amoy: {  // Polygon testnet (replaced Mumbai in 2024)
      url: "https://rpc-amoy.polygon.technology",
      accounts: [process.env.DEPLOYER_PRIVATE_KEY!],
      chainId: 80002
    }
  },
  etherscan: {
    apiKey: {
      polygon: process.env.POLYGONSCAN_API_KEY!,
      polygonAmoy: process.env.POLYGONSCAN_API_KEY!
    },
    customChains: [
      {
        network: "polygonAmoy",
        chainId: 80002,
        urls: {
          apiURL: "https://api-amoy.polygonscan.com/api",
          browserURL: "https://amoy.polygonscan.com"
        }
      }
    ]
  }
}

Important: Mumbai testnet was deprecated in April 2024. Use Amoy (chainId: 80002).

MATIC for Gas

For Amoy: free faucet at faucet.polygon.technology. For mainnet: bridge via Polygon Bridge (from Ethereum) or buy MATIC on exchange and withdraw directly to Polygon network.

Deployment

# Deploy to testnet
npx hardhat run scripts/deploy.ts --network amoy

# Verification on PolygonScan
npx hardhat verify --network amoy DEPLOYED_ADDRESS "constructor_arg1" "constructor_arg2"

# Deploy to mainnet
npx hardhat run scripts/deploy.ts --network polygon
npx hardhat verify --network polygon DEPLOYED_ADDRESS

Deploy script with address saving:

import { ethers } from "hardhat"
import fs from "fs"

async function main() {
  const [deployer] = await ethers.getSigners()
  console.log("Deploying with:", deployer.address)
  console.log("MATIC balance:", ethers.formatEther(await deployer.provider.getBalance(deployer.address)))

  const Contract = await ethers.getContractFactory("MyContract")
  const contract = await Contract.deploy(/* constructor args */)
  await contract.waitForDeployment()

  const address = await contract.getAddress()
  console.log("Deployed to:", address)

  // Save address
  const deployments = { polygon: { MyContract: address, deployedAt: new Date().toISOString() } }
  fs.writeFileSync("deployments.json", JSON.stringify(deployments, null, 2))
}

main().catch(console.error)

Gas Price on Polygon

Polygon uses EIP-1559 with base fee. It is recommended not to set too low maxPriorityFeePerGas — otherwise transaction gets stuck in mempool:

// Get current gas settings
const feeData = await provider.getFeeData()
// maxFeePerGas = baseFee * 2 + maxPriorityFeePerGas (automatically via "auto")

Minimum baseFee on Polygon — 30 gwei (after EIP-1559 upgrade). During network congestion may rise to 300-500 gwei — but in MATIC it is still pennies relative to Ethereum.

Polygon zkEVM

If stronger binding to Ethereum security model is needed — Polygon zkEVM (chainId: 1101) provides validity proofs on L1. Full EVM equivalence (Type 2 zkEVM). Same tools, different RPCs and chainId. Deployment is similar but gas is 3-10 times cheaper than Ethereum mainnet.

Verification and Deployment Security

After deployment mandatory:

1. Source code verification on PolygonScan — users and integrations can see ABI and source
2. Check constructor: passed arguments match expected ones
3. Smoke test basic functions via PolygonScan Read/Write Contract or hardhat task

Timeline

Deploying a ready contract to Polygon Amoy + verification: 2-4 hours (including network setup and getting test tokens). Deployment to mainnet with gas settings check and verification: 4-8 hours. From scratch, including deploy scripts and migrations: up to 2 days.