FAQ

Authentication & Access

• How do I get an API key for Polygon? Sign up at TheRPC.io, open the Dashboard, go to API Keys, and generate one. The same key works for Polygon (chain ID 137) and every other supported network.
• Can I create multiple API keys? Yes. Separate keys per app or environment let you track Compute Unit usage independently, apply different limits, and revoke one key without breaking the rest.
• What if a key is compromised? Revoke it immediately from the dashboard and generate a fresh one. Because keys are independent, rotating one will not disrupt your other Polygon integrations.

API Usage

• HTTP vs WebSocket? Use the HTTP endpoint (https://polygon.therpc.io/YOUR_API_KEY) for single, stateless requests like balance and block reads. Use the WebSocket endpoint (wss://polygon.therpc.io/YOUR_API_KEY) for real-time subscriptions — streaming new Polygon blocks every ~2 seconds and watching contract logs without polling.
• Handling rate limits? Back off exponentially on a -32029 error and retry; if you hit limits consistently, upgrade your plan for a higher Compute Unit allowance.
• Recommended timeouts? Around 30 s for HTTP requests, a 60 s ping/pong interval to keep WebSocket connections alive, and roughly 30 s for subscription operations.

Error Handling

When a Polygon call fails, TheRPC returns a standard JSON-RPC error whose code explains the cause — the table below maps each code to its meaning, from -32700 parse errors to the -32000 to -32099 server-error range. Four practices keep your integration resilient: always check the error field before reading result; retry transient failures with exponential backoff rather than tight loops; log the full error code and message so you can diagnose issues against chain ID 137; and set sensible timeouts so a slow request never hangs your app.

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 non-null receipt, or subscribe via eth_subscribe over WebSocket for real-time updates — well suited to Polygon's ~2-second blocks.
• Ensuring transaction ordering? Sequence transactions by nonce: fetch the next nonce with eth_getTransactionCount and use an application-level queue so each outgoing transaction from an address uses the correct nonce in order.
• Handling chain reorganizations? Wait for several confirmations by watching eth_blockNumber, listen for newHeads via eth_subscribe, and confirm finality with eth_getBlockByNumber. On Polygon PoS, finality firms up as Heimdall checkpoints commit batches of Bor blocks to Ethereum L1, so deeper confirmations give stronger guarantees.

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 reads into a single JSON-RPC array, switch to WebSocket subscriptions for real-time data, cache slowly-changing results, and tune polling intervals to Polygon's ~2-second block time so you do not over-request.
• High-throughput best practices? Use connection pooling to reuse connections, queue requests to smooth out bursts, monitor your rate-limit headers and Compute Unit usage from the dashboard, and consider dedicated infrastructure or a higher plan for sustained heavy Polygon traffic.

Network Specific

• Switching between networks? Just change the endpoint hostname — your API key and request format stay the same across every supported chain. After switching, call net_version to confirm you are connected to the network you intend.
• Does the same code work on Polygon? Yes. Point your existing Ethereum-style code at https://polygon.therpc.io/YOUR_API_KEY and it runs unchanged. Polygon PoS uses chain ID 137 (0x89), which you can verify at any time with eth_chainId.

Development & Integration

• Recommended Web3 libraries? For JavaScript use ethers.js or web3.js, for Python use web3.py, and for the JVM use web3j — all speak standard JSON-RPC and connect to Polygon without special configuration. See Tools & SDKs for the full list.
• Testing your integration? Start on a testnet, use a dedicated test API key, build in error handling from the start, validate connectivity with a simple eth_blockNumber call against chain ID 137, and monitor performance and Compute Unit usage before going to production.