Deploy on Base

Set up a Foundry project, point it at Base, and deploy a contract to Base Sepolia in a single end-to-end workflow.

What you build

By the end of this guide you will have:

• A Foundry-based development environment configured for Base
• A smart contract deployed to Base Sepolia
• A connection pattern your frontend can reuse against your contracts

Tip

Base is a fast, low-cost, builder-friendly Ethereum L2 designed to bring the next billion users onchain. Following this guide plugs you into a wide ecosystem of developers, creators, and operators building the global onchain economy.

Set up your development environment

1. Create a project directory.

mkdir my-base-project && cd my-base-project

2. Install Foundry, the framework used throughout this guide.

curl -L https://foundry.paradigm.xyz | bash
foundryup

The installer pulls Foundry and updates it to the latest release.

3. Initialize a Solidity project.

forge init

The Foundry project is ready. The starter contract sits at src/Counter.sol — this guide uses that contract as the deployment target.

Tip

Foundry packages tools for Ethereum development including Forge (testing), Cast (chain interactions), and Anvil (local node). The full reference is in the Foundry Book.

Configure Foundry for Base

Deploying to Base requires two pieces:

1. An RPC connection to the network
2. A funded private key for signing the deployment transaction

1. Set up your RPC connection

1. Create a .env file at the project root.
2. Add the Base RPC URLs.

BASE_RPC_URL="https://mainnet.base.org"
BASE_SEPOLIA_RPC_URL="https://sepolia.base.org"

3. Load the variables into your shell.

source .env

Tip

Base Sepolia is the test network for Base and is used for the rest of this guide. Free Base Sepolia ETH is available from the faucets list.

2. Secure your private key

1. Import your private key into Foundry’s encrypted keystore.

cast wallet import deployer --interactive

2. Paste the key when prompted and set a password.

The encrypted key is stored at ~/.foundry/keystores, which is excluded from git.

Caution

Never share or commit a private key. Treat it as a credential and store it accordingly.

Deploy your contract

With the environment configured, deploy to Base Sepolia.

1. (Optional) Run a dry run first to confirm the deployment is well-formed.

forge create ./src/Counter.sol:Counter --rpc-url $BASE_SEPOLIA_RPC_URL --account deployer

This simulates the deploy without broadcasting. You will see the transaction details and ABI; nothing is written onchain.

2. Add --broadcast to actually deploy.

forge create ./src/Counter.sol:Counter --rpc-url $BASE_SEPOLIA_RPC_URL --account deployer --broadcast

Tip

The --broadcast flag is required to send the transaction. Without it, Foundry only simulates.

The contract argument follows the format <contract-path>:<contract-name>.

3. A successful deploy prints output similar to:

Deployer: 0x...
Deployed to: 0x...  <-- YOUR CONTRACT ADDRESS
Transaction hash: 0x...

4. Save the deployed address into .env.

COUNTER_CONTRACT_ADDRESS="0x..."

Replace 0x... with the address from the output.

5. Reload the variables.

source .env

Tip

Re-run source .env after every change to load new variables into the current shell.

Verify your deployment

To confirm the contract is live:

1. Look up the transaction hash on Sepolia Basescan.
2. Read the contract directly with cast:

cast call $COUNTER_CONTRACT_ADDRESS "number()(uint256)" --rpc-url $BASE_SEPOLIA_RPC_URL

Tip

The command requires COUNTER_CONTRACT_ADDRESS in .env and a fresh source .env. Otherwise the variable expands to nothing and the call fails.

The call returns the initial value of the Counter’s number storage slot, which is 0.

The contract is now live on Base Sepolia.

Next steps

• Wire a frontend to your contracts using wagmi or viem.
• Dive deeper into Foundry workflows in the Foundry deployment tutorial.