A web-based interface for generating unsigned Ethereum transactions using the pkg/txgenerator package. Supports multiple transaction types including ETH transfers, ERC20, ERC721, and ERC1155 operations.

What it demonstrates

🌐 Web interface for easy transaction generation
🔷 Support for multiple transaction types (ETH, ERC20, ERC721, ERC1155)
⛽ Support for both Legacy and EIP-1559 fee types
📝 Dynamic form fields based on selected transaction type
📄 Returns transactions in JSON format
✅ Comprehensive parameter validation
🔒 Unsigned transactions ready for signing

Run

Prerequisites

Go 1.23.0 or later
No external dependencies required (no RPC endpoints needed)

Running the Example

cd examples/txgenerator-example
go mod tidy
go run .

Access: http://localhost:8080

The server will start and log the access URL. You can also build and run the binary:

go build -o txgenerator-example
./txgenerator-example

Supported Transaction Types

Native ETH

Transfer ETH: Simple native token transfer

ERC20 Tokens

Transfer ERC20: Transfer ERC20 tokens
Approve ERC20: Approve ERC20 token spending

ERC721 Tokens (NFTs)

Transfer ERC721 (transferFrom): Basic NFT transfer
Transfer ERC721 (safeTransferFrom): Safe NFT transfer with recipient check
Approve ERC721: Approve a specific NFT
Set Approval For All ERC721: Approve/revoke operator for all NFTs

ERC1155 Tokens

Transfer ERC1155: Single token transfer
Batch Transfer ERC1155: Batch transfer multiple tokens
Set Approval For All ERC1155: Approve/revoke operator for all tokens

Using the UI

Select Transaction Type: Choose from the dropdown menu
Choose Fee Type:
- Legacy: Uses GasPrice (for older networks)
- EIP-1559: Uses MaxFeePerGas and MaxPriorityFeePerGas (recommended for modern networks)
Fill Common Parameters:
- Nonce: Transaction nonce
- Gas Limit: Maximum gas to use
- Chain ID: Network chain ID (1 for Ethereum mainnet)
- Gas Price (Legacy) or MaxFeePerGas + MaxPriorityFeePerGas (EIP-1559)
Fill Transaction-Specific Parameters: Fields will appear based on selected transaction type
Generate Transaction: Click "Generate Transaction" to get the JSON output

Example Parameters

Transfer ETH

{
  "txType": "transferETH",
  "useEIP1559": false,
  "nonce": "0",
  "gasLimit": "21000",
  "chainID": "1",
  "gasPrice": "20000000000",
  "params": {
    "to": "0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb",
    "value": "1000000000000000000"
  }
}

To: 0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb
Value: 1000000000000000000 (1 ETH in wei)

Transfer ERC20

{
  "txType": "transferERC20",
  "useEIP1559": true,
  "nonce": "0",
  "gasLimit": "65000",
  "chainID": "1",
  "maxFeePerGas": "30000000000",
  "maxPriorityFeePerGas": "2000000000",
  "params": {
    "tokenAddress": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
    "to": "0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb",
    "amount": "1000000"
  }
}

Token Address: 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 (USDC)
To: 0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb
Amount: 1000000 (1 USDC with 6 decimals)

Transfer ERC721

{
  "txType": "safeTransferFromERC721",
  "useEIP1559": true,
  "nonce": "0",
  "gasLimit": "100000",
  "chainID": "1",
  "maxFeePerGas": "30000000000",
  "maxPriorityFeePerGas": "2000000000",
  "params": {
    "tokenAddress": "0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D",
    "from": "0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb",
    "to": "0x8ba1f109551bd432803012645ac136ddd64dba72",
    "tokenID": "1234"
  }
}

Token Address: 0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D (Bored Ape Yacht Club)
From: 0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb
To: 0x8ba1f109551bd432803012645ac136ddd64dba72
Token ID: 1234

Batch Transfer ERC1155

{
  "txType": "batchTransferERC1155",
  "useEIP1559": true,
  "nonce": "0",
  "gasLimit": "200000",
  "chainID": "1",
  "maxFeePerGas": "30000000000",
  "maxPriorityFeePerGas": "2000000000",
  "params": {
    "tokenAddress": "0x...",
    "from": "0x...",
    "to": "0x...",
    "tokenIDs": "1,2,3",
    "values": "10,20,30"
  }
}

Token Address: 0x...
From: 0x...
To: 0x...
Token IDs: 1,2,3 (comma-separated)
Values: 10,20,30 (comma-separated, corresponding to token IDs)

Response Format

The generated transaction is returned in JSON format with the following fields:

{
  "type": "0x0" or "0x2",
  "nonce": "0",
  "gasPrice": "...",
  "maxFeePerGas": "...",
  "maxPriorityFeePerGas": "...",
  "gasLimit": "21000",
  "to": "0x...",
  "value": "...",
  "data": "0x...",
  "chainID": "1",
  "v": "0x...",
  "r": "0x...",
  "s": "0x...",
  "hash": "0x...",
  "raw": "0x..."
}

Code Structure

The example is organized into several files:

main.go - Application entry point, server setup, and HTTP routing
handlers.go - Transaction generation logic and request handling
templates.go - HTML templates and frontend JavaScript for the web interface
go.mod - Go module definition and dependencies

Key Functions

handleHome() - Serves the web interface HTML
handleGenerateTransaction() - Handles POST requests to generate transactions
GenerateTransaction() - Core transaction generation logic based on request type
TransactionToJSON() - Converts transaction to JSON format for response

API

GET / - Web interface
POST /generate - Generate transaction

Request Format

{
  "txType": "transferETH",
  "useEIP1559": false,
  "nonce": "0",
  "gasLimit": "21000",
  "chainID": "1",
  "gasPrice": "20000000000",
  "maxFeePerGas": "",
  "maxPriorityFeePerGas": "",
  "params": {
    "to": "0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb",
    "value": "1000000000000000000"
  }
}

Fee Types

Legacy Transactions (Type 0)

Uses GasPrice field
Compatible with older networks
Example: gasPrice: "20000000000" (20 gwei)

EIP-1559 Transactions (Type 2)

Uses MaxFeePerGas and MaxPriorityFeePerGas fields
Recommended for modern networks (Ethereum after London fork)
Example:
- maxFeePerGas: "30000000000" (30 gwei)
- maxPriorityFeePerGas: "2000000000" (2 gwei)

Dependencies

github.com/ethereum/go-ethereum - Core Ethereum types and transaction structures
github.com/status-im/go-wallet-sdk/pkg/txgenerator - Transaction generation package
github.com/gorilla/mux - HTTP router and URL matcher

Error Handling

The example includes comprehensive error handling for:

Invalid transaction parameters (zero addresses, negative amounts)
Missing required fields
Invalid numeric values
Unsupported transaction types
JSON encoding/decoding errors

All errors are returned as JSON responses with descriptive error messages.

Troubleshooting

"undefined: handleHome" error: Use go run . instead of go run main.go
Invalid Addresses: Ensure addresses are valid Ethereum addresses (0x-prefixed, 40 hex characters)
Missing Parameters: All required fields must be filled based on the selected transaction type
Invalid Amounts: Ensure numeric values are valid (no decimals for wei/token units)
Port Already in Use: Change the port in main.go if 8080 is already in use
Transaction Generation Fails: Check that all required parameters are provided and valid