> ## Documentation Index
> Fetch the complete documentation index at: https://docs.optimism.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Connecting to OP Mainnet

> Documentation for OP Mainnet and OP Sepolia. This page covers network information including network names, chain IDs, RPC endpoints, currency symbols, block explorers, and contract addresses.

This page provides network information for OP Mainnet and OP Sepolia, including RPC endpoints, chain IDs, and block explorers.

<Info>
  The public RPC URLs provided below are rate limited and do not support websocket connections.
  If you are experiencing rate limiting issues or need websocket functionality, consider [running your own node](/node-operators/reference/architecture/rollup-node) or signing up for a [third-party RPC provider](/app-developers/reference/rpc-providers).
</Info>

## OP Mainnet

| Parameter                              | Value                                                                                           |
| -------------------------------------- | ----------------------------------------------------------------------------------------------- |
| Network Name                           | `OP Mainnet`                                                                                    |
| Chain ID                               | `10`                                                                                            |
| Currency Symbol<sup>1</sup>            | ETH                                                                                             |
| Explorer                               | [https://explorer.optimism.io](https://explorer.optimism.io)                                    |
| Public RPC URL                         | [https://mainnet.optimism.io](https://mainnet.optimism.io)                                      |
| Sequencer URL<sup>2</sup>              | [https://mainnet-sequencer.optimism.io](https://mainnet-sequencer.optimism.io)                  |
| Flashblocks websocket URL <sup>3</sup> | [wss://op-mainnet-fb-ws-pub.optimism.io/ws](wss://op-mainnet-fb-ws-pub.optimism.io/ws)          |
| Contract Addresses                     | Refer to the [Contract Addresses page](/op-mainnet/network-information/op-addresses#op-mainnet) |
| Connect Wallet                         | [Click here to connect your wallet to OP Mainnet](https://chainid.link?network=optimism)        |

1. The "currency symbol" is required by some wallets like MetaMask.
2. The sequencer URL is write only.
3. Strictly rate-limited public URL. Please rely on Ethereum JSON RPC or reach out to the Optimism team for a more relaxed private endpoint.

## OP Sepolia

| Parameter                              | Value                                                                                           |
| -------------------------------------- | ----------------------------------------------------------------------------------------------- |
| Network Name                           | `OP Sepolia`                                                                                    |
| Chain ID                               | `11155420`                                                                                      |
| Currency Symbol<sup>1</sup>            | ETH                                                                                             |
| Explorer                               | [https://testnet-explorer.optimism.io](https://testnet-explorer.optimism.io)                    |
| Public RPC URL                         | [https://sepolia.optimism.io](https://sepolia.optimism.io)                                      |
| Flashblocks websocket URL <sup>3</sup> | [wss://op-sepolia-fb-ws.optimism.io/ws](wss://op-sepolia-fb-ws.optimism.io/ws)                  |
| Sequencer URL<sup>2</sup>              | [https://sepolia-sequencer.optimism.io](https://sepolia-sequencer.optimism.io)                  |
| Contract Addresses                     | Refer to the [Contract Addresses page](/op-mainnet/network-information/op-addresses#op-sepolia) |
| Connect Wallet                         | [Click here to connect your wallet to OP Sepolia](https://chainid.link?network=op-sepolia)      |

1. The "currency symbol" is required by some wallets like MetaMask.
2. The sequencer URL is write only.
3. Strictly rate-limited public URL. Please rely on Ethereum JSON RPC or reach out to the Optimism team for a more relaxed private endpoint.