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Polygon

Polygon RPC — Free Endpoint & Developer Guide

Jun 20, 2026·3 min read

Polygon is a widely-used EVM network with low fees and one of the largest ecosystems in web3. This guide shows how to connect to it through MoltNode's free Polygon RPC endpoint — no API key, no signup, just one clean URL.

What is Polygon

Polygon is an EVM-compatible proof-of-stake network that lets developers deploy Solidity contracts and run dApps with low transaction fees and quick confirmations. Because it is EVM-compatible, the standard Ethereum tooling — wallets, libraries, and the full set of eth_* JSON-RPC methods — works the same way it does on Ethereum mainnet. That compatibility, combined with low costs, has made Polygon home to a large ecosystem of DeFi protocols, NFT projects, games, and consumer apps.

The native gas token on Polygon is POL, and its EVM chainId is 137. If you already know how to build on Ethereum, you already know how to build on Polygon — only the network endpoint, chainId, and gas token change.

Polygon RPC endpoint on MoltNode

MoltNode gives Polygon a single, memorable URL:

https://moltnode.ag/polygon

That URL is a live Polygon RPC endpoint. There is no API key to manage and no signup, and CORS is open, so you can call it directly from front-end code in the browser. Send standard JSON-RPC 2.0 requests as an HTTP POST with a JSON body and you get JSON-RPC responses back.

The URL is dual-purpose. A GET to https://moltnode.ag/polygon in a browser returns a human-readable page that explains the chain and how to use it. A POST to the same URL returns machine-readable Polygon JSON-RPC. One link serves both people and programs.

Quick test with curl

The fastest way to verify the free Polygon RPC is working is to fetch the latest block number with eth_blockNumber:

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

The response is a JSON-RPC object with the current block height as a hex string, like {"jsonrpc":"2.0","id":1,"result":"0x..."}.

Use it from your code

Any Ethereum client works, because the endpoint speaks plain JSON-RPC. Point it at the Polygon node URL and start making calls. Here is a viem example:

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

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

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

The same URL works with ethers, web3.py, wagmi, or any wallet that supports custom networks — add it with chainId 137 and symbol POL and you are connected.

Reliability & failover

Behind moltnode.ag/polygon sits a pool of upstream providers tried in order, both backed by Alchemy infrastructure. If the primary upstream is unreachable or returns an error, MoltNode automatically retries against the next one, so a single hiccup does not surface as a failed request. The upstream provider keys live server-side and are never exposed, which means you get reliable infrastructure without ever holding a credential.

There is no hard rate limit, but the endpoint is a shared resource. Use it responsibly: cache results, avoid tight polling loops, and move to a dedicated provider for heavy production traffic. Treating the Polygon JSON-RPC fairly keeps it fast and free for everyone who relies on it.

For humans and agents

MoltNode is built to be discoverable by both developers and autonomous software. A browser GET on https://moltnode.ag/polygon renders a readable page; a POST returns Polygon JSON-RPC. For programmatic discovery, agents and scripts can read the machine-readable catalog at https://moltnode.ag/api/chains to look up Polygon's slug, chainId, and endpoint, and a plain-text overview lives at https://moltnode.ag/llms.txt. An AI agent can discover the chain, confirm chainId 137, and begin issuing eth_* calls with no human involved.

Closing

For a free Polygon RPC that simply works, point your client at https://moltnode.ag/polygon. No key, no signup, open CORS, and automatic failover across upstreams — whether you are building a dApp with viem, scripting in web3.py, adding a custom network to your wallet, or running an AI agent against the Polygon node.