Universal Deployer Contract

The Universal Deployer Contract (UDC) is a singleton smart contract that wraps the deploy syscall to expose it to any contract that doesn’t implement it, such as account contracts. You can think of it as a standardized generic factory for Starknet contracts.

Since Starknet has no deployment transaction type, it offers a standardized way to deploy smart contracts by following the Standard Deployer Interface and emitting a ContractDeployed event.

For details on the motivation and the decision making process, see the Universal Deployer Contract proposal.

UDC contract address

The UDC address is deployed at address 0x04a64cd09a853868621d94cae9952b106f2c36a3f81260f85de6696c6b050221 in Mainnet and Sepolia testnet.

Interface

trait IUniversalDeployer {
    fn deploy_contract(
        class_hash: ClassHash,
        salt: felt252,
        from_zero: bool,
        calldata: Span<felt252>
    ) -> ContractAddress;
}

Deploying a contract with the UDC

First, declare the target contract (if it’s not already declared). Next, call the UDC’s deploy_contract method. Here’s an implementation example in Cairo:

use openzeppelin::utils::interfaces::{IUniversalDeployerDispatcher, IUniversalDeployerDispatcherTrait};

const UDC_ADDRESS: felt252 = 0x04a64cd09a853868621d94cae9952b106f2c36a3f81260f85de6696c6b050221;

fn deploy() -> ContractAddress {
    let dispatcher = IUniversalDeployerDispatcher {
        contract_address: UDC_ADDRESS.try_into().unwrap()
    };

    // Deployment parameters
    let class_hash = class_hash_const::<
       0x5c478ee27f2112411f86f207605b2e2c58cdb647bac0df27f660ef2252359c6
    >();
    let salt = 1234567879;
    let from_zero = false;
    let mut calldata = array![];

    // The UDC returns the deployed contract address
    dispatcher.deploy_contract(class_hash, salt, from_zero, calldata.span())
}

Deployment types

The Universal Deployer Contract offers two types of addresses to deploy: origin-dependent and origin-independent. As the names suggest, the origin-dependent type includes the deployer’s address in the address calculation, whereas, the origin-independent type does not. The from_zero boolean parameter ultimately determines the type of deployment.

When deploying a contract that uses get_caller_address in the constructor calldata, remember that the UDC, not the account, deploys that contract. Therefore, querying get_caller_address in a contract’s constructor returns the UDC’s address, not the account’s address.

Origin-dependent

By making deployments dependent upon the origin address, users can reserve a whole address space to prevent someone else from taking ownership of the address.

Only the owner of the origin address can deploy to those addresses.

Achieving this type of deployment necessitates that the origin sets from_zero to false in the deploy_contract call. Under the hood, the function passes a modified salt to the deploy_syscall, which is the hash of the origin’s address with the given salt.

To deploy a unique contract address pass:

let deployed_addr = udc.deploy_contract(class_hash, salt, false, calldata.span());

Origin-independent

Origin-independent contract deployments create contract addresses independent of the deployer and the UDC instance. Instead, only the class hash, salt, and constructor arguments determine the address. This type of deployment enables redeployments of accounts and known systems across multiple networks. To deploy a reproducible deployment, set from_zero to true.

let deployed_addr = udc.deploy_contract(class_hash, salt, true, calldata.span());

Version changes

See the previous Universal Deployer API for the initial spec.

The latest iteration of the UDC includes some notable changes to the API which include:

Origin-dependent deployments previously meant that the unique argument would be true. Origin-dependent deployments from the new UDC iteration, however, requires that from_zero is false. It’s especially important to keep this in mind when dealing with ContractDeployed events because this change will appear as the opposite boolean per deployment type.

Precomputing contract addresses

This library offers utility functions written in Cairo to precompute contract addresses. They include the generic calculate_contract_address_from_deploy_syscall as well as the UDC-specific calculate_contract_address_from_udc. Check out the deployments for more information.

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