BSC API: Endpoints, Methods, and Developer Setup

BSC API Decision Checklist

Before integrating the BSC API, consider these key points:

• Endpoint type: Public, shared, or dedicated RPC? Public endpoints are rate-limited; dedicated nodes offer consistent performance.
• Archive vs. full node: Archive nodes provide historical state data; full nodes only recent. Choose based on your data needs.
• WebSocket support: For real-time subscriptions (e.g., pending transactions, logs), ensure your provider supports WSS.
• Rate limits: Check the allowed requests per second/second (RPS) and monthly quota. Production apps need headroom.
• Geographic latency: Select endpoints close to your user base or use a global load balancer.
• Debug and trace APIs: Required for transaction simulation and advanced monitoring; not enabled on all providers.
• Pricing model: Pay-as-you-go vs. flat fee. Estimate your call volume before committing.

See our RPC pricing and supported networks for more details.

Quick Introduction to BSC API

The BSC API refers to the JSON-RPC interface exposed by BNB Smart Chain (BSC) nodes. Because BSC is EVM-compatible, the API is almost identical to Ethereum's JSON-RPC – methods like eth_blockNumber, eth_getBalance, and eth_sendRawTransaction work the same way. This means existing Ethereum tooling (Hardhat, Foundry, viem, web3.js) can target BSC with minimal changes.

BSC adds a few BEP-specific methods for its finality mechanism and blob support. Understanding these helps you build more reliable dapps.

BSC API Endpoints Overview

BSC endpoints come in three main types:

• Public RPC: Free, but severely rate-limited (e.g., 5–10 req/s). Use only for testing.
• Shared/Service RPC: Provided by infrastructure platforms like OnFinality. Higher limits, archive data, often with WebSocket and trace APIs.
• Dedicated Node: A standalone instance with guaranteed resources, full control, and no noisy neighbours.

For production, a service RPC or dedicated node is recommended. You can find BSC endpoints on our networks page.

BSC JSON-RPC Methods

Here are the most commonly used methods grouped by category:

Most EVM libraries abstract these methods. You rarely call them directly; instead, use the library's API.

Connecting to BSC API

Here's how to connect to the BSC mainnet using curl and viem (JavaScript):

Using curl

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

Using viem (JavaScript)

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

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

async function main() {
  const blockNumber = await client.getBlockNumber();
  console.log('Current BSC block:', blockNumber);
}

main();

WebSocket subscription

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

const client = createPublicClient({
  chain: bsc,
  transport: webSocket('wss://rpc.onfinality.io/bsc/ws')
});

const unwatch = await client.watchBlockNumber({
  onBlockNumber: (blockNumber) => console.log('New block:', blockNumber),
});

Common Pitfalls and Troubleshooting

• Rate limiting: Public endpoints often return 429 Too Many Requests. Use a service with higher limits or dedicated nodes.
• Finality confirmation: BSC has probabilistic finality (~15 blocks) plus economic finality (BEP-126). For irreversible transactions, wait for eth_getFinalizedBlock or at least 15 confirmations.
• Archive data missing: If you need past states (e.g., historical token balances), ensure your endpoint has archive data enabled.
• WebSocket drops: Unstable connections can cause subscription loss. Implement reconnection logic with exponential backoff.
• Gas estimation failures: If eth_estimateGas reverts, check the sender balance and contract logic. Use eth_call with stateOverride for debugging.

Deciding Between Shared vs. Dedicated BSC API

For small to medium workloads, a shared RPC service is cost-effective. High-volume or latency-sensitive projects benefit from dedicated nodes.

Key Takeaways

• BSC API is EVM-compatible; most Ethereum tools work unchanged on chain ID 56.
• Choose endpoints based on workload: public for testing, service RPC for production, dedicated for high throughput.
• BSC-specific methods like eth_getFinalizedBlock help confirm finality faster.
• Always check rate limits, archive support, and WebSocket availability before building.
• OnFinality provides BSC mainnet and testnet RPC endpoints with shared and dedicated options.