What is the BNB Smart Chain RPC URL and how do I use it?

Quick answer: the BNB Smart Chain RPC URL

The BNB Smart Chain (BSC) RPC URL is the endpoint your application uses to communicate with the BSC network via JSON-RPC. The official OnFinality public endpoint is:

https://bnb.api.onfinality.io/public

This URL works for both HTTP and WebSocket connections. You can use it in MetaMask, Hardhat, ethers.js, viem, or any other Web3 tool that supports custom RPC endpoints.

Chain settings at a glance

Before you connect, make sure your configuration matches the BSC mainnet parameters:

For testnet development, use the BNB Chain Testnet with chain ID 97 and the endpoint https://bnb-testnet.api.onfinality.io/public.

How to configure the RPC URL in a wallet

If you want to add BSC to MetaMask or another wallet, use the chain settings above. Here is an example for MetaMask:

1. Open MetaMask and click the network dropdown.
2. Click Add Network.
3. Fill in the details:
   • Network Name: BNB Smart Chain
   • New RPC URL: https://bnb.api.onfinality.io/public
   • Chain ID: 56
   • Currency Symbol: BNB
   • Block Explorer URL: https://bscscan.com
4. Click Save.

Now your wallet can interact with BSC.

Using the RPC URL in code

Here is how to use the endpoint with ethers.js and viem.

ethers.js

const { ethers } = require("ethers");

const provider = new ethers.JsonRpcProvider("https://bnb.api.onfinality.io/public");

async function getBlockNumber() {
  const blockNumber = await provider.getBlockNumber();
  console.log("Current block:", blockNumber);
}

getBlockNumber();

viem

import { createPublicClient, http } from 'viem';
import { bsc } from 'viem/chains';

const client = createPublicClient({
  chain: bsc,
  transport: http('https://bnb.api.onfinality.io/public'),
});

const blockNumber = await client.getBlockNumber();
console.log('Current block:', blockNumber);

Public vs. managed RPC: which should you use?

Public RPC endpoints like the one above are great for development, testing, and low-traffic applications. However, they are shared across many users, which can lead to rate limiting and slower responses during peak times.

For production applications, you should consider a managed RPC provider. OnFinality offers RPC pricing and supported RPC networks that include BSC. Managed endpoints provide higher reliability, better performance, and dedicated options.

How to choose an RPC provider for BSC

When evaluating RPC providers for BSC, consider these factors:

OnFinality offers both shared and dedicated BSC nodes. For high-throughput workloads, a dedicated node gives you more consistent performance. See our BNB Chain RPC provider comparison for more details.

Common RPC errors and how to debug them

Here are some common issues you might encounter when using a BSC RPC URL:

Debugging with curl

You can test your RPC endpoint with a simple curl command:

curl -X POST https://bnb.api.onfinality.io/public \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

A successful response looks like:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x1a2b3c"
}

WebSocket subscriptions

For real-time data, use the WebSocket endpoint. Here is an example with ethers.js:

const { ethers } = require("ethers");

const provider = new ethers.WebSocketProvider("wss://bnb.api.onfinality.io/public/ws");

provider.on("block", (blockNumber) => {
  console.log("New block:", blockNumber);
});

Key Takeaways

• The BNB Smart Chain RPC URL is the gateway to BSC for your dApp or wallet.
• The OnFinality public endpoint is https://bnb.api.onfinality.io/public.
• Always verify chain ID (56) and other settings when configuring your environment.
• For production, consider a managed RPC provider for better reliability and performance.
• Use the debugging tips above to resolve common RPC issues quickly.

Frequently Asked Questions

What is the BNB Smart Chain RPC URL?

The official OnFinality public RPC URL is https://bnb.api.onfinality.io/public. It supports HTTP and WebSocket.

Can I use the BSC RPC URL for free?

Yes, the public endpoint is free for development and light usage. For production, check RPC pricing for managed options.

What is the BSC testnet RPC URL?

The BNB Chain Testnet RPC URL is https://bnb-testnet.api.onfinality.io/public with chain ID 97.

How do I add BSC to MetaMask?

Use the chain settings provided in this article to add BSC as a custom network.

What should I do if I get rate limited?

Switch to a managed RPC provider or implement retry logic with exponential backoff. OnFinality offers scalable options for production workloads.