explorer-contract-verification

name: explorer-contract-verification description: Verify smart contracts on Etherscan, Routescan, and Blockscout block explorers. This skill should be used when the user asks to "verify contract", "verify on etherscan", "verify on blockscout", "verify on routescan", "verify on chain scan". Handles standard verification, Etherscan V2 API, Routescan, Blockscout verification, proxy patterns, and factory-created contracts.

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.