FAQ

Authentication & Access

• How do I get an API key for Arbitrum One? Sign up at TheRPC.io, open the Dashboard, go to the API Keys section, and generate a key. Use it with https://arbitrum.therpc.io/YOUR_API_KEY.
• Can I create multiple API keys? Yes. Separate keys per environment (dev, staging, production) and per application let you scope usage, track metrics independently, and revoke one without disrupting the others.
• What if a key is compromised? Revoke it immediately from the dashboard, then generate a fresh key and update your environment variables. The old key stops working as soon as it is revoked.

API Usage

• HTTP vs WebSocket on Arbitrum One? Use the HTTP endpoint for single, simple requests like reading a balance or block. Use the WebSocket endpoint for real-time subscriptions — given Arbitrum One's sub-second soft confirmations, eth_subscribe lets you react to new heads and logs without polling.
• How do I handle rate limits? Retry with exponential backoff on a -32029 error, and if you hit the ceiling consistently, consider upgrading your plan for higher throughput.
• Recommended timeouts? Around 30 seconds for HTTP requests, a 60-second ping/pong interval to keep WebSocket connections alive, and roughly 30 seconds for subscription operations.

Error Handling

The Arbitrum One API uses the standard JSON-RPC error codes shown in the table below: -32700 parse error, -32600 invalid request, -32601 method not found, -32602 invalid params, -32603 internal error, and the -32000 to -32099 range for server errors. Four practices keep your integration robust: always check the error field before reading result, retry transient failures with exponential backoff, log the full error code and message for diagnosis, and handle timeouts so a slow call never hangs your application.

Common Error Response

1{
2  "jsonrpc": "2.0",
3  "error": {
4    "code": -32601,
5    "message": "Method not found"
6  },
7  "id": 1
8}

Standard JSON-RPC Error Codes

Technical Questions

• Tracking pending transactions: poll eth_getTransactionReceipt until it returns a receipt, or subscribe to updates in real time with eth_subscribe over WebSocket — well suited to Arbitrum One's fast sequencer confirmations.
• Ensuring request ordering: sequence transactions from an address by nonce, retrieved via eth_getTransactionCount, and use an application-level queue so you never submit two transactions with the same nonce.
• Handling reorganizations: the sequencer gives fast soft confirmations, but final settlement follows the L1 challenge window. Wait for confirmations by watching eth_blockNumber, listen to newHeads via eth_subscribe, and re-verify a block with eth_getBlockByNumber before treating a high-value transaction as final.

Transaction Tracking Example

1// Example of transaction tracking
2const receipt = await web3.eth.getTransactionReceipt(txHash);
3if (receipt) {
4  console.log(`Transaction confirmed in block ${receipt.blockNumber}`);
5}

Performance

• Optimizing API usage: batch multiple calls into a single JSON-RPC request, switch to WebSocket subscriptions for real-time data, cache slowly-changing results, and tune polling intervals to your actual needs rather than polling aggressively.
• High-throughput best practices: use connection pooling, queue requests to smooth bursts, monitor your rate-limit headers and dashboard metrics, and consider dedicated infrastructure if you run heavy indexing or trading workloads against Arbitrum One protocols like GMX or Uniswap.

Network Specific

• Switching networks: just change the endpoint URL — the same API key and identical request format work across every network TheRPC serves. Confirm the active network with net_version after switching.
• Reusing code across chains: your Arbitrum One integration carries over unchanged to other chains by swapping only the endpoint host. Arbitrum One's chain ID is 42161 (hex 0xa4b1), which you can verify at runtime with eth_chainId.

Development & Integration

• Recommended Web3 libraries: JavaScript and TypeScript developers use web3.js or ethers.js, Python developers use web3.py, and JVM developers use web3j. See the Tools & SDKs page for coverage in other languages — all of them work against the Arbitrum One endpoint unchanged because it is fully Ethereum-compatible.
• Testing your integration: start on a testnet with a test API key, build in error handling from the start, validate connectivity with a simple eth_blockNumber call, and monitor performance before moving to production traffic on chain 42161.