Skip to main content

DevChain Template

The nethereum-devchain template gives you a complete local Ethereum development environment — a JSON-RPC node, a blockchain indexer, a Blazor explorer, and a PostgreSQL database — all orchestrated by .NET Aspire. It's the simplest way to get a local chain running for development and testing.

What You'll Build​

By the end of this guide, you'll have four services running together:

  • DevChain — an in-memory Ethereum node with EIP-1559, debug tracing, and pre-funded accounts
  • Indexer — a background worker that indexes blocks, transactions, token transfers, and MUD records into PostgreSQL
  • Explorer — a full Blazor blockchain explorer with contract interaction, ABI decoding, and wallet connection
  • PostgreSQL — a managed database container for all indexed data

Prerequisites​

Step 1: Install the Template Pack​

dotnet new install Nethereum.Aspire.TemplatePack

This installs both the nethereum-devchain and nethereum-dapp templates. You only need to run this once.

Step 2: Create the Project​

dotnet new nethereum-devchain -n MyChain
cd MyChain

This creates a solution with four projects:

MyChain/
├── AppHost/          Aspire orchestrator — wires everything together
├── DevChain/         Ethereum node
├── Indexer/          Block/transaction indexer
├── Explorer/         Blazor blockchain explorer
└── ServiceDefaults/  Shared Aspire configuration (health checks, telemetry)

You can customise the chain ID or package versions at creation time:

dotnet new nethereum-devchain -n MyChain --ChainId 42069 --NethereumVersion 6.0.4

Step 3: Set the Dev Account Private Key​

The Explorer uses a pre-funded account for contract deployment and interaction. Set it via user secrets:

cd AppHost
dotnet user-secrets set "Parameters:devAccountPrivateKey" "5de4111afa1a4b94908f83103eb1f1706367c2e68ca870fc3fb9a804cdab365a"
cd ..

This is the default Hardhat/Foundry account #2 with 10,000 ETH. Use any funded account you prefer.

Step 4: Run the Solution​

dotnet run --project AppHost

The Aspire dashboard opens automatically (typically at https://localhost:17178). You'll see all four services starting up with health indicators.

Step 5: Explore the Dashboard​

From the Aspire dashboard you can:

  • View service health — green means healthy, click for details
  • Read logs — each service's console output in real-time
  • Trace requests — distributed traces across DevChain → Indexer → Explorer
  • Click through to endpoints — the Explorer and DevChain URLs are clickable

Click the Explorer endpoint to open the blockchain explorer. You'll see the genesis block and any transactions generated by the system.

Step 6: Interact with the DevChain​

The DevChain exposes a standard JSON-RPC endpoint. Connect any Ethereum tool to the URL shown in the Aspire dashboard.

With Nethereum:

var web3 = new Web3("http://localhost:<port>");
var balance = await web3.Eth.GetBalance.SendRequestAsync("0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266");

With Foundry:

cast balance 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266 --rpc-url http://localhost:<port>

With curl:

curl -X POST http://localhost:<port> \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

Replace <port> with the actual port from the Aspire dashboard.

Configuration​

DevChain Storage​

By default, the DevChain persists state to SQLite so your chain survives restarts. For ephemeral testing:

{
  "DevChain": {
    "Storage": "memory",
    "ChainId": 31337,
    "AutoMine": true
  }
}

Explorer Options​

The Explorer connects to DevChain and PostgreSQL automatically via Aspire service discovery. The AppHost also configures a dev account for contract interaction and enables pending transaction display:

var explorer = builder.AddProject<Projects.Explorer>("explorer")
    .WithReference(postgres)
    .WithReference(devchain)
    .WaitFor(indexer)
    .WithEnvironment("Explorer__DevAccountPrivateKey", devAccountKey)
    .WithEnvironment("Explorer__EnablePendingTransactions", "true");

Next Steps​

Now that you have a running DevChain environment, you're ready to build on top of it:

  • dApp Template — Add a WebApp, Solidity contracts, and wallet integration to create a full-stack dApp
  • DevChain Quickstart — Learn more about the DevChain library itself — configuration, storage modes, RPC methods, and forking