.env

This page covers deploying FHEVM contracts with Foundry — to a local Anvil node or to Sepolia.

Deploy to Sepolia

The Sepolia FHEVM stack is already deployed at the canonical addresses listed in Contract addresses. Your forge script just needs to broadcast against a Sepolia RPC — your contract picks up the FHEVM addresses through ZamaEthereumConfig (or whichever Zama config it inherits).

{% stepper %}

{% step %}

Configure environment variables

Copy the template's .env.example and fill in the values:

cp .env.example .env

# .env
DEPLOYER_PRIVATE_KEY=0x...
RPC_URL=https://sepolia.infura.io/v3/<key>
# ETHERSCAN_API_KEY=...   # optional, for verification

source .env

{% hint style="info" %} If you only have a mnemonic / seed phrase, derive the private key with Foundry's cast:

cast wallet private-key "your twelve or twenty four words here"

{% endhint %}

{% endstep %}

{% step %}

Run the deploy script

forge script script/DeployFHECounter.s.sol \
    --rpc-url $RPC_URL \
    --private-key $DEPLOYER_PRIVATE_KEY \
    --broadcast --verify

{% endstep %}

{% endstepper %}

Deploy to a local Anvil node

For local development, you must first deploy a local FHEVM host stack before deploying your own contract. This is provided by forge-fhevm via its deploy-local.sh script.

The local FHEVM host stack is a cleartext FHEVM where encrypted values are stored as plaintexts on-chain — nothing is actually encrypted, but every contract code path executes the same as on a real chain.

{% stepper %}

{% step %}

Clone forge-fhevm alongside your project

git clone https://github.com/zama-ai/forge-fhevm

{% endstep %}

{% step %}

Start an Anvil node

In a separate terminal:

anvil

{% endstep %}

{% step %}

Deploy the FHEVM host stack to the local node

From the forge-fhevm directory:

./deploy-local.sh

This materializes all FHEVM host contracts (FHEVMExecutor, ACL, InputVerifier, KMSVerifier) at their canonical addresses on the running Anvil node, using setCode/setStorageAt.

{% hint style="info" %} deploy-local.sh is local-first and zero-config. It uses the addresses committed in FHEVMHostAddresses.sol and works out of the box with no .env file for the standard local setup that ZamaConfig._getLocalConfig() expects. {% endhint %}

{% endstep %}

{% step %}

Deploy your contract

From your project directory:

forge script script/DeployFHECounter.s.sol \
    --rpc-url http://localhost:8545 \
    --broadcast

{% endstep %}

{% endstepper %}

Multiple local nodes

deploy-local.sh can fan out to several Anvil instances from a single build:

# Deploy to two local nodes concurrently
./deploy-local.sh --anvil-port 8545 --anvil-port 8546

# Reuse already-built artifacts
./deploy-local.sh --skip-build --anvil-port 8545 --anvil-port 8546

Where to go next

🟨 Go to Contract addresses for the canonical FHEVM addresses on each network.

🟨 Go to Write FHEVM tests in Foundry for the test side of the workflow.