Summary
Polygon Mainnet is the proof-of-stake, EVM-compatible chain identified by chain ID 137. If you searched for "polygon mainnet," you most likely need to connect a wallet, a dApp, or a backend service to it and want the correct chain settings and a working RPC endpoint without guessing.
This page gives you the chain settings first, then a public OnFinality endpoint you can test immediately, then the checks that separate a quick demo from a production-ready connection. It also explains when a public endpoint is enough and when a dedicated node or managed RPC plan makes more sense.
Polygon Mainnet is not the same as Polygon Amoy, the testnet. Keep the two separate in your config: the mainnet chain ID is 137, while Amoy uses 80002. Mixing them up is one of the most common reasons a deployment looks connected but never confirms a transaction.
Key Takeaways
- Polygon Mainnet uses chain ID 137, native currency POL with 18 decimals, and the explorer at polygonscan.com.
- A public OnFinality endpoint for Polygon Mainnet is https://polygon.api.onfinality.io/public; it is useful for testing and light reads.
- Wallet, dApp, and backend configs must all point to chain ID 137, not the Amoy testnet chain ID 80002.
- Production workloads usually need a managed or dedicated endpoint with clear rate limits, WebSocket support, and monitoring.
- Most connection failures trace back to wrong chain ID, a stale or rate-limited endpoint, or a method the endpoint does not support.
- OnFinality offers Polygon RPC API access and dedicated node options; check the network page and pricing page for current details.
Polygon Mainnet settings at a glance
Before you touch any code, confirm the four values that every EVM tool needs: chain ID, currency symbol, decimals, and a working RPC URL. For Polygon Mainnet these are stable and widely used, so a mismatch almost always means a copy-paste error or a leftover testnet value.
The table below is the reference you can paste into a wallet, a Hardhat config, or a viem chain definition. If a tool asks for a network ID as well as a chain ID, use 137 for both on Polygon Mainnet.
| Criterion | What to check | Why it matters |
|---|---|---|
| Chain ID | 137 (hex 0x89) | Wrong chain ID sends transactions to the wrong network or causes wallet rejection. |
| Native currency | POL, 18 decimals | Gas is paid in POL; older configs that still say MATIC may confuse users but the network is the same. |
| Public OnFinality RPC URL | https://polygon.api.onfinality.io/public | A quick endpoint for testing reads and wallet connection. |
| Block explorer | https://polygonscan.com | Use it to confirm transactions, contract addresses, and block numbers. |
| Transport | HTTP and WebSocket | HTTP suits request/response calls; WebSocket is needed for subscriptions. |
Quick recommendation: public endpoint or managed plan?
Use the public OnFinality endpoint when you are wiring up a wallet, running a quick script, or checking that your contract address resolves. It is a fast way to confirm chain settings without signing up for anything.
Move to a managed RPC API key or a dedicated node when your app has real users, background jobs, or indexers hitting Polygon Mainnet continuously. Shared public endpoints are not designed to absorb production traffic, and a single noisy client can degrade everyone's experience.
If you are unsure, start public, measure your request volume for a day, then decide. The RPC pricing page and the Polygon network page give you the concrete options to compare.
- Prototype or wallet setup: public endpoint is fine.
- Staging with realistic traffic: managed RPC API key.
- High-volume reads, indexers, or latency-sensitive writes: evaluate dedicated nodes.
- Need WebSocket subscriptions in production: confirm transport support before committing.
Connect with curl, viem, and a wallet
The fastest sanity check is a single JSON-RPC call. If eth_chainId returns 0x89, you are talking to Polygon Mainnet. If it returns 0x13882, you are on Amoy and need to switch endpoints.
For application code, viem lets you define a chain and point it at any RPC URL. Keep the URL in an environment variable so you can swap between public, managed, and dedicated endpoints without editing source.
curl -X POST https://polygon.api.onfinality.io/public -H 'Content-Type: application/json' -d '{"jsonrpc":"2.0","id":1,"method":"eth_chainId","params":[]}'- Expect result 0x89 for Polygon Mainnet.
- In viem, create a chain object with id 137 and rpcUrls.default.http set to your endpoint.
- In MetaMask, add a network with chain ID 137, symbol POL, and the RPC URL above.
Failure modes and how to debug them
Most Polygon Mainnet connection problems fall into a small set of categories. Match the symptom to the likely cause before you change code, because the fix is usually configuration rather than logic.
If a call works in curl but fails in your app, compare the exact URL, headers, and chain ID the app is using. Environment variables that were copied from a testnet setup are a frequent culprit.
| Criterion | What to check | Why it matters |
|---|---|---|
| Wallet shows wrong network | Chain ID is 137, not 80002 | Amoy is a testnet; transactions there do not affect mainnet balances. |
| eth_call returns empty or reverts | Contract address and ABI match mainnet deployment | Testnet addresses often differ from mainnet ones. |
| Intermittent 429 or timeouts | Request volume against endpoint limits | Public endpoints are shared; sustained load needs a managed plan. |
| WebSocket subscription drops | Transport support and reconnect logic | Long-lived subscriptions need a provider that supports ws and a client that reconnects. |
| eth_getLogs times out | Block range size and filter specificity | Very wide log queries are expensive; narrow the range or use an indexer. |
Production readiness checklist
Before you point real users at a Polygon Mainnet endpoint, walk through the items below. They are the difference between a demo that works on your laptop and a service that behaves predictably under load.
Keep at least one fallback endpoint configured. Even a well-run provider can have maintenance windows, and a fallback URL in your client config turns a hard outage into a brief degradation.
- Endpoint URL stored in environment config, not hardcoded.
- Chain ID asserted at startup so a misconfigured environment fails fast.
- Fallback RPC URL configured for read paths.
- Monitoring on error rate, latency, and block height lag.
- WebSocket reconnect logic if you use subscriptions.
- Log retention for failed transactions so you can reproduce issues.
When to move from public RPC to OnFinality infrastructure
OnFinality provides RPC API access and dedicated node infrastructure for Polygon Mainnet. The RPC API is the natural next step after the public endpoint: you get a managed URL and a clearer picture of your usage. Dedicated nodes are for teams that need isolated capacity or specific transport requirements.
You do not have to decide all at once. Start with the public endpoint, move to a managed plan when traffic grows, and evaluate dedicated nodes when your workload becomes predictable enough to size. The supported RPC networks page shows what else is available if you run multi-chain infrastructure.
- Managed RPC API: good default for most production apps.
- Dedicated node: better fit for high sustained throughput or strict isolation.
- Multi-chain teams: keep endpoint conventions consistent across networks.
- Always confirm current transport support and limits on the network page.
Frequently Asked Questions
What is the Polygon Mainnet chain ID?
Polygon Mainnet uses chain ID 137, which is 0x89 in hex. Polygon Amoy, the testnet, uses 80002. Always confirm the chain ID your wallet or app reports before sending transactions.
What is the public OnFinality RPC URL for Polygon Mainnet?
The public endpoint is https://polygon.api.onfinality.io/public. It supports HTTP and WebSocket and is suitable for testing and light usage. For production traffic, use a managed RPC API key or a dedicated node.
Is Polygon Mainnet the same as Polygon PoS?
Polygon Mainnet is commonly referred to as Polygon PoS. It is an EVM-compatible proof-of-stake chain that settles checkpoints to Ethereum. The native gas token is POL, which replaced MATIC in naming.
How do I add Polygon Mainnet to MetaMask?
Open the network settings, add a custom network, and enter chain ID 137, currency symbol POL, the RPC URL from OnFinality, and https://polygonscan.com as the explorer. Save and switch to the network.
Why does my Polygon Mainnet call fail with a rate limit error?
Public endpoints are shared and have limits. If you see 429 responses or timeouts under load, move to a managed RPC plan or a dedicated node so your traffic has its own capacity.
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