Contract Verification with Foundry

This guide shows you how to verify your smart contracts using Foundry on the Filecoin network.

Prerequisites

• A Foundry project set up for Filecoin development. If you don't have one, start with the FEVM Foundry Kit.
• Foundry installed with forge and cast available in your PATH.
• A deployed contract address on Filecoin mainnet or Calibration testnet.
• The same source tree, compiler version, optimizer settings, and foundry.toml settings that were used for deployment.
• Contract constructor arguments, if the contract was deployed with any.
• A Filecoin RPC URL for the target network. Filecoin mainnet uses chain ID 314; Calibration testnet uses chain ID 314159.

Verification Methods

Set RPC URLs in your shell before running the examples:

export FILECOIN_RPC_URL=https://api.node.glif.io/rpc/v1
export CALIBRATION_RPC_URL=https://api.calibration.node.glif.io/rpc/v1

Blockscout Verification

Blockscout is a popular blockchain explorer that supports contract verification.

Verify on Calibration testnet:

forge verify-contract \
  --rpc-url "$CALIBRATION_RPC_URL" \
  --chain 314159 \
  --verifier blockscout \
  --verifier-url "https://filecoin-testnet.blockscout.com/api/" \
  0xYourContractAddress \
  src/MyContract.sol:MyContract

Verify on Filecoin mainnet:

forge verify-contract \
  --rpc-url "$FILECOIN_RPC_URL" \
  --chain 314 \
  --verifier blockscout \
  --verifier-url "https://filecoin.blockscout.com/api/" \
  0xYourContractAddress \
  src/MyContract.sol:MyContract

For constructors, pass ABI-encoded constructor arguments. The constructor signature and values must match the deployment:

CONSTRUCTOR_ARGS=$(cast abi-encode "constructor(string,string)" "MyToken" "MYT")

forge verify-contract \
  --rpc-url "$CALIBRATION_RPC_URL" \
  --chain 314159 \
  --verifier blockscout \
  --verifier-url "https://filecoin-testnet.blockscout.com/api/" \
  --constructor-args "$CONSTRUCTOR_ARGS" \
  0xYourContractAddress \
  src/MyToken.sol:MyToken

If Blockscout reports that the contract is already verified while you are retrying the same address, add --force --skip-is-verified-check.

Sourcify Verification

Sourcify provides decentralized contract verification.

Verify on Filecoin mainnet:

forge verify-contract \
  --rpc-url "$FILECOIN_RPC_URL" \
  --chain 314 \
  --verifier sourcify \
  --verifier-url https://sourcify.dev/server/ \
  --guess-constructor-args \
  0xYourContractAddress \
  src/MyToken.sol:MyToken

Verify on Calibration testnet:

forge verify-contract \
  --rpc-url "$CALIBRATION_RPC_URL" \
  --chain 314159 \
  --verifier sourcify \
  --verifier-url https://sourcify.dev/server/ \
  --guess-constructor-args \
  0xYourContractAddress \
  src/MyToken.sol:MyToken

For more information, see the Sourcify documentation.

Filfox Verification

Filfox is the native Filecoin explorer with dedicated verification support.

Installation:

npm install --save-dev @fil-b/filfox-verifier

Usage:

npx filfox-verifier forge <address> <contract-path> --chain <chainId>

Examples:

# Verify on Filecoin mainnet
npx filfox-verifier forge 0xYourContractAddress src/MyContract.sol:MyContract --chain 314

# Verify on Calibration testnet
npx filfox-verifier forge 0xYourContractAddress src/MyContract.sol:MyContract --chain 314159

The Filfox verifier requires Node.js 20 or later and a Foundry project with foundry.toml. It runs forge build and extracts the metadata needed for the Filfox verification request.

For detailed information, see the @fil-b/filfox-verifier documentation.