openscan-hardhat-links

A Hardhat plugin that automatically launches the OpenScan Explorer webapp and adds OpenScan links to all transaction logs.

Installation

To install this plugin, run the following command:

npm install --save-dev openscan-hardhat-links

In your hardhat.config.ts file, import the plugin and add it to the plugins array:

import { defineConfig } from "hardhat/config";
import openScanPlugin from "openscan-hardhat-links";

export default defineConfig({
  plugins: [openScanPlugin],
  networks: {
    ...
  },
  openScan: {
    url: "http://localhost:3030",
    chainId: 31337,
  },
});

Features

This plugin provides two main features:

1. Automatic OpenScan Explorer Launch: When you start the Hardhat node, the plugin automatically:

   • Launches a local OpenScan Explorer webapp on port 3030
   • Opens your default browser to http://localhost:3030
   • Serves the explorer from the plugin's built-in webapp

2. OpenScan Links in Logs: All transaction-related logs include clickable OpenScan links:

   • Transaction hashes → OpenScan transaction view
   • Addresses → OpenScan address view
   • Blocks → OpenScan block view
   • Contract deployments → OpenScan contract view

Usage

Simply start your Hardhat node:

npx hardhat node

The OpenScan Explorer will automatically launch and your browser will open to the explorer interface. All subsequent transactions will include OpenScan links in the console output

How It Works

Webapp Launch

The plugin hooks into Hardhat's network lifecycle using the newConnection hook. When the Hardhat node starts:

1. The hook detects the first network connection
2. Checks if port 3030 is available (fails fast if not)
3. Starts a custom HTTP server serving static files from the built-in explorer webapp
4. Opens your default browser to the explorer URL
5. Logs a success message with a clickable link

The webapp continues running as long as the Hardhat node is active and automatically cleans up when the node stops.

Transaction Logging

The plugin uses the onRequest network hook to intercept all JSON-RPC requests. For relevant methods (like eth_sendTransaction, eth_getTransactionReceipt, etc.), it extracts transaction hashes, addresses, and block numbers, then outputs clickable OpenScan links to the console.

Requirements

• Hardhat 3.x
• Node.js 24+
• Port 3030 must be available

Troubleshooting

Port 8545 or 3030 Already in Use

If you see an error about port 8545 or 3030 being in use, you need to free up that port:

kill -9 $(lsof -t -i:8545)
kill -9 $(lsof -t -i:3030)