Verify using Foundry

Learn how to verify smart contracts on the Filecoin network using Foundry with various verification services including Blockscout, Sourcify, and Filfox.

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.