In-Memory Node

Learn how to setup a local in-memory era_test_node.

This section provides instructions on setting up and using the In-Memory Node, era_test_node, for local testing. It covers installation, network forking, transaction details viewing, replaying transactions, and testing local bootloader and system contracts.

Please keep in mind that era-test-node is still in its alpha stage, some features might not be fully supported yet and may not work as fully intended. It is open-sourced and contributions are welcomed.

Understand the In-Memory Node

The In-Memory Node uses an in-memory database for storing state information and simplified hashmaps for tracking blocks and transactions. In fork mode, it retrieves missing storage data from a remote source when not available locally. Moreover it also uses the remote server (openchain) to resolve the ABI and topics to human readable names.

You can visit the era-test-node repository to learn more.

Run actions with zksync-cli

You can setup the In-Memory Node quickly with zksync-cli dev start. If you don't have zksync-cli setup, see the Overview guide.

Note: at the moment this method won't allow you to use additional features like forking networks or replaying transactions.

Install and set up era_test_node

  1. Download era_test_node from latest Release.
  2. Extract the binary and mark as executable:
    tar xz -f /path/to/downloaded/binary/era_test_node.tar.gz -C /usr/local/bin/
    chmod +x /usr/local/bin/era_test_node
  3. Start the node:
    era_test_node run

The expected output will be as follows:

12:34:56 [INFO] Starting network with chain id: L2ChainId(260)
12:34:56 [INFO] Rich Accounts
12:34:56 [INFO] =============
12:34:56 [INFO] Account #0: 0x36615Cf349d7F6344891B1e7CA7C72883F5dc049 (1_000_000_000_000 ETH)
12:34:56 [INFO] Private Key: 0x7726827caac94a7f9e1b160f7ea819f172f7b6f9d2a97f992c38edeab82d4110
12:34:56 [INFO]
12:34:56 [INFO] Account #1: 0xa61464658AfeAf65CccaaFD3a512b69A83B77618 (1_000_000_000_000 ETH)
12:34:56 [INFO] Private Key: 0xac1e735be8536c6534bb4f17f06f6afc73b2b5ba84ac2cfb12f7461b20c0bbe3


12:34:56 [INFO] Account #9: 0xE90E12261CCb0F3F7976Ae611A29e84a6A85f424 (1_000_000_000_000 ETH)
12:34:56 [INFO] Private Key: 0x3eb15da85647edd9a1159a4a13b9e7c56877c4eb33f614546d4db06a51868b1c
12:34:56 [INFO]
12:34:56 [INFO] ========================================
12:34:56 [INFO]   Node is ready at
12:34:56 [INFO] ========================================
When utilizing era_test_node with MetaMask, it's essential to note that any restart of the in-memory node will necessitate a reset of MetaMask's cached account data (nonce, etc). In the MetaMask app, navigate to 'Settings', then 'Advanced', and finally, select 'Clear activity tab data'.

Network details

The era_test_node has the following default network configurations:

  • L2 RPC: http://localhost:8011
  • Network Id: 260

These can be configured to your preference.

Please note that the existing implementation does not facilitate communication with Layer 1. As a result, an L1 RPC is not available.

Fork a network

To fork the mainnet, use the following command, replacing [network] with either mainnet or sepolia-testnet:

era_test_node fork [network]

This command starts the node, forked at the current head of the selected network.

You also have the option to specify a custom http endpoint and a custom forking height:

era_test_node fork --fork-at 7000000 mainnet

Replay remote transactions locally

If you wish to replay a remote transaction locally for deep debugging, use the following command:

era_test_node replay_tx sepolia-testnet 0x7119045573862797257e4441ff48bf5a3bc4d133a00d167c18dc955eda12cfac

For more detailed transaction information, such as call traces, add the --show-calls flag. If you want to see ABI names, add the --resolve-hashes flag:

era_test_node --show-calls=user \
--resolve-hashes replay_tx sepolia-testnet \

Alternatively (if your node is already running) you can use config_setShowCalls and config_setResolveHashes RPC endpoints to configure these values:

# era_test_node already running...

# Set show-calls to User
curl --request POST \
  --url http://localhost:8011/ \
  --header 'content-type: application/json' \
  --data '{"jsonrpc": "2.0","id": "1","method": "config_setShowCalls","params": ["user"]}'

# Enable resolve-hashes
curl --request POST \
  --url http://localhost:8011/ \
  --header 'content-type: application/json' \
  --data '{"jsonrpc": "2.0","id": "1","method": "config_setResolveHashes","params": [true]}'

Here's an example of what you should expect to see when show-calls and resolve-hashes are configured:

Send network calls

You can send network calls against a running era_test_node.

Launch the local in-memory node:

era_test_node fork sepolia-testnet
  • Use curl to send a network call:
    curl --request POST \
      --url http://localhost:8011 \
      --header 'Content-Type: application/json' \
      --data '{
        "jsonrpc": "2.0",
        "id": 1,
        "method": "eth_call",
        "params": [
  • Use foundry-zksync. Make sure to install and configure foundry-zksync before proceeding (for installation instructions, please see Foundry with ZKsync Era):
    cast call 0xe1134444211593Cfda9fc9eCc7B43208615556E2 \
      "name()(string)" \
      --rpc-url http://localhost:8011

    Retrieve the balance of a particular contract:
    cast call 0x40609141Db628BeEE3BfAB8034Fc2D8278D0Cc78 \
      "balanceOf(address)(uint256)"  \
      0x40609141Db628BeEE3BfAB8034Fc2D8278D0Cc78  \
      --rpc-url http://localhost:8011

Deploy contracts

For the deployment of your contracts, you have the flexibility to choose between two preferred methods: either by using Hardhat with the @matter-labs/hardhat-zksync plugin, or via foundry-zksync.

The following example will detail the process using foundry-zksync.

Before proceeding, ensure that you've compiled your contracts using forge build --zksync.

forge create contracts/Greeter.sol:Greeter \
  --constructor-args "ZKsync and Foundry" \
  --private-key 7726827caac94a7f9e1b160f7ea819f172f7b6f9d2a97f992c38edeab82d4110 \
  --rpc-url http://localhost:8011 \
  --chain 260 \

Test bootloader and system contracts

In-memory node allows testing of the currently compiled bootloader and system contracts. This makes it possible to examine the effects of changes on already deployed contracts.

These commands assume you have set $ZKSYNC_HOME in your shell profile file (e.g. ~/.bash_profile, ~/.zshrc) to target your local copy of era_test_node. For instance,
export ZKSYNC_HOME=/path/to/era_test_node

  1. Preprocess and compile the contracts:
    cd etc/system-contracts
    yarn preprocess && yarn hardhat run ./scripts/compile-yul.ts
  2. To use the locally compiled bootloader and system contracts, run:
    RUST_LOG=vm=trace era_test_node --dev-use-local-contracts fork sepolia-testnet

Pre-configured rich wallets

In-Memory node includes pre-configured "rich" accounts for testing:

  • Address: 0x36615Cf349d7F6344891B1e7CA7C72883F5dc049
    Private Key: 0x7726827caac94a7f9e1b160f7ea819f172f7b6f9d2a97f992c38edeab82d4110
  • Address: 0xa61464658AfeAf65CccaaFD3a512b69A83B77618
    Private Key: 0xac1e735be8536c6534bb4f17f06f6afc73b2b5ba84ac2cfb12f7461b20c0bbe3
  • Address: 0x0D43eB5B8a47bA8900d84AA36656c92024e9772e
    Private Key: 0xd293c684d884d56f8d6abd64fc76757d3664904e309a0645baf8522ab6366d9e
  • Address: 0xA13c10C0D5bd6f79041B9835c63f91de35A15883
    Private Key: 0x850683b40d4a740aa6e745f889a6fdc8327be76e122f5aba645a5b02d0248db8
  • Address: 0x8002cD98Cfb563492A6fB3E7C8243b7B9Ad4cc92
    Private Key: 0xf12e28c0eb1ef4ff90478f6805b68d63737b7f33abfa091601140805da450d93
  • Address: 0x4F9133D1d3F50011A6859807C837bdCB31Aaab13
    Private Key: 0xe667e57a9b8aaa6709e51ff7d093f1c5b73b63f9987e4ab4aa9a5c699e024ee8
  • Address: 0xbd29A1B981925B94eEc5c4F1125AF02a2Ec4d1cA
    Private Key: 0x28a574ab2de8a00364d5dd4b07c4f2f574ef7fcc2a86a197f65abaec836d1959
  • Address: 0xedB6F5B4aab3dD95C7806Af42881FF12BE7e9daa
    Private Key: 0x74d8b3a188f7260f67698eb44da07397a298df5427df681ef68c45b34b61f998
  • Address: 0xe706e60ab5Dc512C36A4646D719b889F398cbBcB
    Private Key: 0xbe79721778b48bcc679b78edac0ce48306a8578186ffcb9f2ee455ae6efeace1
  • Address: 0xE90E12261CCb0F3F7976Ae611A29e84a6A85f424
    Private Key: 0x3eb15da85647edd9a1159a4a13b9e7c56877c4eb33f614546d4db06a51868b1c

Writing and running tests locally

This section demonstrates how to author and execute tests locally against era_test_node using the mocha and chai testing frameworks with Hardhat.

Project configuration

  1. Start by creating a new Hardhat project. If you need guidance, follow the getting started guide.
  2. To incorporate the test libraries, execute:
      yarn add -D mocha chai @types/mocha @types/chai
  3. Add the following lines to your package.json in the root folder:
    "scripts": {
        "test": "NODE_ENV=test hardhat test"

This script makes it possible to run tests in a Hardhat environment with the NODE_ENV env variable set as test.

Configure tests

Adjust hardhat.config.ts to use the local node for testing:

Ensure era_test_node is running in another process before executing the test command.
import "@matterlabs/hardhat-zksync";

module.exports = {
  zksolc: {
    version: "latest",
    settings: {},
  defaultNetwork: "zkSyncTestnet",
  networks: {
    hardhat: {
      zksync: true,
    zkSyncTestnet: {
      url: "http://localhost:8011",
      ethNetwork: "http://localhost:8545",
      zksync: true,
  solidity: {
    version: "0.8.17",

Write test scripts

Construct a test/main.test.ts file with the following code:

import { expect } from "chai";
import { Wallet, Provider, Contract } from "zksync-ethers";
import * as hre from "hardhat";
import { Deployer } from "@matterlabs/hardhat-zksync";

const RICH_WALLET_PK = "0x7726827caac94a7f9e1b160f7ea819f172f7b6f9d2a97f992c38edeab82d4110";

describe("Greeter", function () {
  it("Should return the new greeting once it's changed", async function () {
    const provider = Provider.getDefaultProvider();

    const wallet = new Wallet(RICH_WALLET_PK, provider);
    const deployer = new Deployer(hre, wallet);

    const artifact = await deployer.loadArtifact("Greeter");
    const greeter = await deployer.deploy(artifact, ["Hi"]);

    expect(await greeter.greet()).to.eq("Hi");

    const setGreetingTx = await greeter.setGreeting("Hola, mundo!");
    // wait until the transaction is mined
    await setGreetingTx.wait();

    expect(await greeter.greet()).to.equal("Hola, mundo!");

To run the test file, execute:

  npm test

Well done! You've successfully run your first local tests with ZKsync Era and era_test_node.


If running era_test_node run provides the following error:

“era_test_node” can’t be opened because Apple cannot check it for malicious software.
This software needs to be updated. Contact the developer for more information.

You may require the use of sudo. On macOS, the binary may need to have its quarantine attribute cleared:

xattr -d /usr/local/bin/era_test_node

Made with ❤️ by the ZKsync Community