eth_getCode | zkSync Era RPC Docs

Get contract bytecode on zkSync Era. Essential for verifying smart contracts for RWA tokenization ($1.9B, 25% market share), hyperchain deployment via ZK Stack, and cross-chain DeFi.

Returns the bytecode at a given address on zkSync Era.

Why zkSync? Build on Matter Labs' flagship zkEVM powering the Elastic Network of interoperable hyperchains with ZK Stack modular framework, hyperchain interoperability, native account abstraction, and $1.9B in tokenized real-world assets.

When to Use This Method

eth_getCode is essential for ZK developers, RWA tokenization teams, and builders launching custom L2/L3 chains:

Contract Verification -- Verify that the bytecode deployed at an address matches the expected source code compilation output on zkSync
EOA vs Contract Detection -- Determine whether an address is an externally owned account (returns 0x) or a deployed smart contract (returns bytecode)
Proxy Pattern Detection -- Check if a proxy contract has been initialized by examining whether its implementation slot contains code
Security Auditing -- Validate contract deployments before interacting with them on RWA tokenization ($1.9B, 25% market share), hyperchain deployment via ZK Stack, and cross-chain DeFi

Common Use Cases

1. Detect Contract vs EOA

Determine if an address is a smart contract or a regular wallet on zkSync:

JavaScript

import { JsonRpcProvider } from 'ethers';

const provider = new JsonRpcProvider('https://api-zksync-era-mainnet-full.n.dwellir.com/YOUR_API_KEY');

async function isContract(address) {
  const code = await provider.getCode(address);
  return code !== '0x' && code !== '0x0';
}

async function classifyAddress(address) {
  if (await isContract(address)) {
    const balance = await provider.getBalance(address);
    console.log('Contract at', address, '- balance:', balance.toString());
    return 'contract';
  }
  console.log('EOA at', address);
  return 'eoa';
}

2. Verify Proxy Implementation Initialization

Check whether a proxy contract has been initialized with an implementation on zkSync:

JavaScript

import { JsonRpcProvider } from 'ethers';

const provider = new JsonRpcProvider('https://api-zksync-era-mainnet-full.n.dwellir.com/YOUR_API_KEY');

async function checkProxyInitialized(proxyAddress) {
  // EIP-1967 implementation slot
  const IMPL_SLOT = '0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc';
  
  const slotValue = await provider.getStorage(proxyAddress, IMPL_SLOT);
  const implAddress = '0x' + slotValue.slice(26);
  
  const implCode = await provider.getCode(implAddress);
  const hasCode = implCode !== '0x' && implCode !== '0x0';
  
  console.log(`Proxy: ${proxyAddress}`);
  console.log(`Implementation: ${implAddress} (has code: ${hasCode})`);
  
  return hasCode;
}

3. Batch Contract Detection

Scan multiple addresses to classify them efficiently:

JavaScript

async function scanAddresses(provider, addresses) {
  const results = [];
  
  for (const address of addresses) {
    try {
      const code = await provider.getCode(address);
      const type = (code === '0x' || code === '0x0') ? 'EOA' : 'Contract';
      results.push({ address, type, bytecodeSize: code.length });
    } catch (error) {
      results.push({ address, type: 'Error', error: error.message });
    }
  }
  
  const summary = {
    total: results.length,
    contracts: results.filter(r => r.type === 'Contract').length,
    eoas: results.filter(r => r.type === 'EOA').length,
    errors: results.filter(r => r.type === 'Error').length
  };
  
  console.log('Scan results:', summary);
  return { results, summary };
}

Best Practices

Check both 0x and 0x0 return values -- different client implementations return one or the other for EOAs
Use historical block numbers with eth_getCode to verify contract state at a specific point in time
For proxy pattern detection, combine eth_getCode with eth_getStorageAt to fully verify initialization
Cache bytecode by address, as deployed contract code is immutable
The return value length is roughly 2x the deployment bytecode size (hex encoding doubles the byte count)

Code Examples

eth_getBalance - Get account balance
eth_getStorageAt - Get contract storage

eth_getCode - zkSync RPC Method

When to Use This Method

Common Use Cases

1. Detect Contract vs EOA

2. Verify Proxy Implementation Initialization

3. Batch Contract Detection

Best Practices

Code Examples

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