HTTP Server & CLI

The Quick Start showed how to run DevChain in-process with CreateWeb3. When you need external tools to connect — MetaMask, Foundry, Hardhat, ethers.js, or any Ethereum client — DevChain can also run as a standalone HTTP JSON-RPC server. This is the .NET equivalent of npx hardhat node or anvil, with the same default mnemonic and compatible RPC methods.

Prerequisites

Install the server as a .NET global tool:

dotnet tool install -g Nethereum.DevChain.Server

Or add it as a project dependency for embedding:

dotnet add package Nethereum.DevChain.Server

Start the Server

Run with defaults — 10 funded accounts, port 8545, auto-mine:

nethereum-devchain

The startup banner shows all funded accounts with their addresses and private keys, just like Hardhat or Anvil:

Nethereum DevChain v5.x.x
========================

RPC endpoint: http://127.0.0.1:8545
Chain ID:     31337
Gas limit:    30,000,000
Mining:       auto

Available Accounts
==================
(0) 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266 (10000 ETH)
(1) 0x70997970C51812dc3A010C7d01b50e0d17dc79C8 (10000 ETH)
...

Private Keys
==================
(0) 0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80
(1) 0x59c6995e998f97a5a0044966f0945389dc9e86dae88c7a8412f4603b6b78690d
...

HD Wallet
==================
Mnemonic: test test test test test test test test test test test junk
Path:     m/44'/60'/0'/0/{index}

The default mnemonic and derivation path match Hardhat and Anvil, so existing test scripts work without changes.

CLI Options

Customise the server with command-line flags:

# Custom port and more accounts
nethereum-devchain -p 8546 -a 20

# Higher account balance (in ETH)
nethereum-devchain -e 100000

# Interval mining (1 block per second)
nethereum-devchain -b 1000

# Fork mainnet
nethereum-devchain -f https://eth.llamarpc.com --fork-block 19000000

# Persistent storage
nethereum-devchain --persist ./mychain

# Fully in-memory
nethereum-devchain --in-memory

# Custom mnemonic
nethereum-devchain -m "your twelve word mnemonic phrase here"

Full Option Reference

Flag	Description	Default
-p, --port	HTTP port	8545
--host	Bind address	127.0.0.1
-a, --accounts	Number of funded accounts	10
-m, --mnemonic	HD wallet mnemonic	Hardhat default
-e, --balance	Account balance in ETH	10000
-c, --chain-id	Chain ID	31337
-b, --block-time	Block time in ms (0 = auto-mine)	0
--gas-limit	Block gas limit	30000000
-f, --fork	Fork from this RPC URL	—
--fork-block	Fork at specific block number	latest
--persist [DIR]	Persist data to disk	./chaindata
--in-memory	Use fully in-memory storage	—
-v, --verbose	Enable verbose logging	—

Connecting from External Tools

The server exposes a standard JSON-RPC endpoint at POST / and a health check at GET /.

From Nethereum (C#)

using Nethereum.Web3;
using Nethereum.Web3.Accounts;

var account = new Account("0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80");
var web3 = new Web3(account, "http://127.0.0.1:8545");

var balance = await web3.Eth.GetBalance.SendRequestAsync(account.Address);

From ethers.js

const { ethers } = require("ethers");
const provider = new ethers.JsonRpcProvider("http://127.0.0.1:8545");
const signer = new ethers.Wallet(
  "0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80",
  provider
);

From curl

curl -X POST http://127.0.0.1:8545 \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

Supported RPC Methods

DevChain supports the complete Ethereum JSON-RPC specification plus development methods:

Category	Methods
Network	web3_clientVersion, web3_sha3, net_version, net_listening, net_peerCount, eth_chainId, eth_syncing, eth_mining, eth_coinbase, eth_accounts
Blocks	eth_blockNumber, eth_getBlockByHash, eth_getBlockByNumber, eth_getBlockTransactionCountByHash, eth_getBlockTransactionCountByNumber, eth_getBlockReceipts
Transactions	eth_sendRawTransaction, eth_getTransactionByHash, eth_getTransactionReceipt, eth_getTransactionByBlockHashAndIndex, eth_getTransactionByBlockNumberAndIndex
State	eth_getBalance, eth_getCode, eth_getStorageAt, eth_getTransactionCount
Execution	eth_call, eth_estimateGas, eth_createAccessList
Gas & Fees	eth_gasPrice, eth_maxPriorityFeePerGas, eth_feeHistory
Filters	eth_newFilter, eth_newBlockFilter, eth_getFilterChanges, eth_getFilterLogs, eth_uninstallFilter, eth_getLogs
Proofs	eth_getProof
Debug	debug_traceTransaction, debug_traceCall

Development Methods

These match Hardhat and Anvil conventions:

Method	Description
evm_mine	Mine a block
evm_snapshot	Take a state snapshot
evm_revert	Revert to a snapshot
evm_increaseTime	Advance the block timestamp
evm_setNextBlockTimestamp	Set exact next block timestamp
hardhat_setBalance	Override an account's ETH balance
hardhat_setCode	Deploy bytecode at an address
hardhat_setNonce	Set an account's nonce
hardhat_setStorageAt	Write to a contract's storage slot
hardhat_impersonateAccount	Sign transactions as any address
hardhat_stopImpersonatingAccount	Stop impersonating

Anvil aliases are also registered for: anvil_setBalance, anvil_setCode, anvil_setNonce, anvil_setStorageAt, anvil_mine, anvil_snapshot, anvil_revert.

Storage Modes

The server supports three storage configurations:

Mode	Flag	Blocks/TXs/Receipts	Account State	Cleanup
SQLite (default)	none	SQLite temp file	In-memory	Auto-delete on exit
SQLite persistent	--persist [DIR]	SQLite at DIR/chain.db	In-memory	Kept between restarts
In-memory	--in-memory	In-memory	In-memory	Lost on exit

Use --persist when you want chain history to survive restarts. Use --in-memory for CI/CD or ephemeral test environments where speed matters most.

Embedding in ASP.NET

Instead of running the CLI, you can embed the DevChain server directly in your ASP.NET application:

using Nethereum.DevChain.Server.Configuration;
using Nethereum.DevChain.Server.Hosting;
using Nethereum.DevChain.Server.Server;

var builder = WebApplication.CreateBuilder(args);

var config = new DevChainServerConfig
{
    ChainId = 31337,
    Port = 8545,
    Storage = "memory"
};

builder.Services.AddDevChainServer(config);
builder.Services.AddHostedService<DevChainHostedService>();

var app = builder.Build();
app.Run();

AddDevChainServer registers the DevChainNode, DevAccountManager, RpcDispatcher, and all storage providers as singletons. DevChainHostedService starts the node when the application starts and stops it on shutdown.

Configuration via appsettings.json

When embedding, you can also bind configuration from appsettings.json:

{
  "DevChain": {
    "ChainId": 31337,
    "Port": 8545,
    "AutoMine": true,
    "BlockTime": 0,
    "AccountCount": 10,
    "Storage": "sqlite",
    "Persist": false
  }
}

Hardhat/Anvil Migration

If you're switching from Hardhat or Anvil to DevChain:

Feature	Hardhat	Anvil	DevChain
Start command	npx hardhat node	anvil	nethereum-devchain
Default port	8545	8545	8545
Default chain ID	31337	31337	31337
Default mnemonic	Same	Same	Same
Fork support	--fork <url>	--fork-url <url>	-f <url>
Persistent storage	No	No	--persist
Interval mining	--interval <sec>	-b <sec>	-b <ms> (milliseconds)
Account impersonation	hardhat_impersonateAccount	anvil_impersonateAccount	hardhat_impersonateAccount
Debug tracing	Limited	debug_traceTransaction	Both geth-compatible

The key difference: DevChain block time is in milliseconds, not seconds.

Next Steps

• Testing Patterns — write isolated integration tests with snapshot/revert
• Forking & State Manipulation — fork mainnet and override account state
• Debug & Trace — trace transactions at the opcode level
• For the complete server API, see the Nethereum.DevChain.Server package reference