Explorer Contract Verification

Overview

Contract verification on Etherscan, Routescan, and Blockscout explorers using Foundry's forge verify-contract. Covers standard Etherscan verification, unsupported chains via Etherscan V2 API, Routescan, Blockscout verification, proxy patterns, and factory-created contracts.

When to Use

• Verify deployed smart contracts on Etherscan, Routescan, or Blockscout explorers
• Verify proxy contracts (ERC1967, UUPS)
• Verify factory-created contracts (CREATE2)
• Extract constructor arguments from deployment data

Prerequisites

Version Check

Before proceeding, verify Foundry version:

forge -V

Stop if version is below 1.3.6.

Chain Reference

Determine the correct verification method by looking up the target chain below.

Etherscan Chains

Routescan Chains

Blockscout Chains

Verification Methods

Method 1: Etherscan — Native Support

For chains Foundry supports natively:

FOUNDRY_PROFILE=optimized forge verify-contract \
  <CONTRACT_ADDRESS> \
  src/<Contract>.sol:<Contract> \
  --rpc-url <chain_name> \
  --verifier etherscan \
  --etherscan-api-key $ETHERSCAN_API_KEY \
  --watch

Method 2: Etherscan V2 API

When Foundry shows "No known Etherscan API URL for chain X", or for any Etherscan chain:

FOUNDRY_PROFILE=optimized forge verify-contract \
  <CONTRACT_ADDRESS> \
  src/<Contract>.sol:<Contract> \
  --verifier etherscan \
  --verifier-url "https://api.etherscan.io/v2/api?chainid=<CHAIN_ID>" \
  --etherscan-api-key $ETHERSCAN_API_KEY \
  --watch

Supported chains: https://docs.etherscan.io/supported-chains

Method 3: Routescan

For chains using Routescan explorers (avalanche, chiliz). Look up the verifier URL from the Routescan Chains table above. Uses --verifier etherscan with a Routescan URL.

FOUNDRY_PROFILE=optimized forge verify-contract \
  <CONTRACT_ADDRESS> \
  src/<Contract>.sol:<Contract> \
  --verifier etherscan \
  --verifier-url "<ROUTESCAN_VERIFIER_URL>" \
  --etherscan-api-key "verifyContract" \
  --watch

Note: Routescan does not require a real API key — pass "verifyContract" as the value.

Method 4: Blockscout

For chains using Blockscout explorers. Look up the verifier URL from the Blockscout Chains table above.

FOUNDRY_PROFILE=optimized forge verify-contract \
  <CONTRACT_ADDRESS> \
  src/<Contract>.sol:<Contract> \
  --verifier blockscout \
  --verifier-url "<BLOCKSCOUT_VERIFIER_URL>" \
  --etherscan-api-key "verifyContract" \
  --watch

Note: Blockscout does not require a real API key — pass "verifyContract" as the value.

Constructor Arguments

Append --constructor-args to any method above when the contract has constructor parameters:

--constructor-args <ABI_ENCODED_ARGS>

Generate constructor args with cast abi-encode:

cast abi-encode "constructor(address,uint256)" 0x123... 1000

Special Cases

Reference: ./references/special-cases.md

Proxy Contracts

Verify implementation and proxy separately. See reference for ERC1967 pattern.

Factory-Created Contracts

Extract constructor args from broadcast initCode using scripts/extract_constructor_args.py.

Library Verification

For libraries, use full path:

src/libraries/<Library>.sol:<Library>

Troubleshooting

Reference: ./references/troubleshooting.md

Common Issues

Output

After successful verification:

• Contract source visible on explorer
• ABI available for interaction
• Constructor args decoded
• "Contract Source Code Verified" badge

Examples

Reference: ./references/examples.md for real-world verification examples from Monad deployment.