leo new

Create a new Leo project with the standard directory structure

The leo new command creates a new Leo project with the standard directory structure and template files.

Syntax

leo new <NAME> [OPTIONS]

Arguments

NAME · string · required

The name of the package to create. This will be used as the program name and directory name.

Options

-n, --network · string · default: "testnet"

Name of the network to use. Options: mainnet, testnet, canary.

-e, --endpoint · string · default: "http://localhost:3030"

Endpoint to retrieve network state from.

Examples

Create a New Project

leo new hello_world

This creates a directory structure:

hello_world/
├── program.json          # Package manifest
├── .env                  # Environment variables (gitignored)
├── .gitignore           # Git ignore rules
├── README.md            # Project README
└── src/
    └── main.leo         # Main program file

Create with Network Configuration

leo new my_program --network testnet --endpoint https://api.explorer.provable.com/v1

Project Structure

program.json

The manifest file contains project metadata:

{
  "program": "hello_world.aleo",
  "version": "0.1.0",
  "description": "",
  "license": "MIT",
  "leo": "2.0.0"
}

src/main.leo

The main program file includes a template:

program hello_world.aleo {
    transition main(public a: u32, b: u32) -> u32 {
        return a + b;
    }
}

.env

Environment variables for development:

NETWORK=testnet
ENDPOINT=https://api.explorer.provable.com/v1

The .env file is automatically added to .gitignore to prevent committing sensitive information.

After Creating a Project

cd hello_world
leo build
leo test
leo run main 1u32 2u32

Best Practices

• Use lowercase with underscores for project names (e.g., my_program)
• The project name becomes the program identifier with .aleo suffix
• Review the generated program.json and update the description and license
• Add your private key to .env for development (never commit this file)

Never use production private keys in .env files. Use test keys for development.

Next Steps

• Build your program
• Run tests
• Execute locally