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

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Syntax

leo new <NAME> [OPTIONS]

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Arguments

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

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Options

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-n, --network
string
default:"testnet"
Name of the network to use. Options: mainnet, testnet, canary.
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-e, --endpoint
string
default:"http://localhost:3030"
Endpoint to retrieve network state from.

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Examples

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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

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Create with Network Configuration

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

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Project Structure

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program.json

The manifest file contains project metadata: 
{
  "program": "hello_world.aleo",
  "version": "0.1.0",
  "description": "",
  "license": "MIT",
  "leo": "2.0.0"
}

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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;
    }
}

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.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.

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After Creating a Project

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

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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.

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Next Steps