zkSync Era RPC — Free Endpoint & Developer Guide

zkSync Era is an Ethereum layer-2 ZK-rollup built with the ZK Stack. This guide shows how to connect to it through MoltNode's free zkSync Era RPC endpoint — no API key, no signup, just one clean URL.

What is zkSync Era

zkSync Era is a zero-knowledge rollup that scales Ethereum by executing transactions off the base layer and posting validity proofs back to Ethereum. Validity proofs let the network confirm that off-chain execution was correct, so users inherit Ethereum's security while paying a fraction of mainnet fees. zkSync Era is built with the ZK Stack, the open framework used to launch ZK-powered chains, and is EVM-compatible: it runs Solidity contracts and answers the standard eth_* JSON-RPC methods, so most Ethereum tooling works against it directly.

The native gas token on zkSync Era is ETH, and its EVM chainId is 324. While the network supports the familiar Ethereum JSON-RPC surface, it also has its own account-abstraction-first design and some zks_* extension methods; for everyday reads and writes — block numbers, balances, logs, sending raw transactions — the standard eth_* calls are exactly what you use.

zkSync Era RPC endpoint on MoltNode

MoltNode gives zkSync Era a single, memorable URL:

https://moltnode.ag/zksync

That URL is a live zkSync Era RPC endpoint. There is no API key to manage, no dashboard to sign up for, and CORS is open so you can call it directly from a browser-based dApp. Send standard JSON-RPC 2.0 requests as an HTTP POST with a JSON body, and you get JSON-RPC responses back.

The same URL is dual-purpose. If you GET https://moltnode.ag/zksync in a browser, you get a human-readable page describing the chain and how to use it. If you POST to it, you get machine-readable zkSync JSON-RPC. One link works for both people and programs.

Quick test with curl

The simplest way to confirm the free zkSync RPC is live is to ask for the latest block number using eth_blockNumber:

curl -s https://moltnode.ag/zksync \
  -X POST \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"eth_blockNumber","params":[]}'

You will get a JSON-RPC response with the current block height as a hex string, for example {"jsonrpc":"2.0","id":1,"result":"0x..."}.

Use it from your code

Because the endpoint speaks plain JSON-RPC, any Ethereum client works. Point it at the zkSync node URL and you are done. Here is an example with viem:

import { createPublicClient, http } from "viem";
import { zksync } from "viem/chains";

const client = createPublicClient({
  chain: zksync,
  transport: http("https://moltnode.ag/zksync"),
});

const block = await client.getBlockNumber();
console.log("Latest zkSync Era block:", block);

The same URL drops into ethers, web3.py, wagmi, or any wallet that lets you add a custom network — just use chainId 324, symbol ETH, and the MoltNode URL as the RPC.

Reliability & failover

Behind moltnode.ag/zksync sits a pool of upstream providers tried in order. Requests are routed to BlockPI, and the gateway is built so that additional upstreams can be added and tried automatically if one is unreachable or returns an error. You do not see this happen — you just get an answer. The upstream provider keys live server-side and are never exposed to clients, so you get production-grade infrastructure without holding any credentials.

The endpoint has no hard rate limit, but it is a shared resource. Please use it responsibly: cache where you can, avoid tight polling loops, and consider a dedicated provider for heavy production workloads. Treating the zkSync JSON-RPC fairly keeps it fast and free for everyone.

For humans and agents

MoltNode is designed to be discoverable by both developers and autonomous software. A browser GET on https://moltnode.ag/zksync renders a readable page; a POST returns zkSync JSON-RPC. For programmatic discovery, AI agents and scripts can read the full machine-readable catalog at https://moltnode.ag/api/chains to find zkSync Era's slug, chainId, and endpoint, and there is a plain-text summary at https://moltnode.ag/llms.txt describing how the gateway works. An agent can find the chain, confirm chainId 324, and start sending eth_* calls with no human in the loop.

Closing

For a free zkSync Era RPC that just works, point your client at https://moltnode.ag/zksync. No key, no signup, open CORS, and automatic failover across upstreams — whether you are building a dApp with viem, scripting with web3.py, adding a custom network to a wallet, or wiring up an AI agent.