# Mainstream Chain Configuration Quick Reference

## EVM Mainnets

| Chain | Chain ID | RPC | Explorer |
|----|---------|-----|---------|
| **Ethereum** | 1 | https://eth.llamarpc.com | etherscan.io |
| **Polygon** | 137 | https://polygon.llamarpc.com | polygonscan.com |
| **Arbitrum One** | 42161 | https://arb1.arbitrum.io/rpc | arbiscan.io |
| **Optimism** | 10 | https://mainnet.optimism.io | optimistic.etherscan.io |
| **Base** | 8453 | https://mainnet.base.org | basescan.org |
| **BSC** | 56 | https://bsc-dataseed.binance.org | bscscan.com |
| **Avalanche C** | 43114 | https://api.avax.network/ext/bc/C/rpc | snowtrace.io |
| **Linea** | 59144 | https://rpc.linea.build | lineascan.build |
| **zkSync Era** | 324 | https://mainnet.era.zksync.io | explorer.zksync.io |
| **Scroll** | 534352 | https://rpc.scroll.io | scrollscan.com |

## EVM Testnets

| Chain | Chain ID | RPC | Faucet |
|----|---------|-----|--------|
| **Sepolia** | 11155111 | https://rpc.sepolia.org | sepoliafaucet.com |
| **Holesky** | 17000 | https://rpc.holesky.ethpandaops.io | faucet.holesky.ethpandaops.io |
| **Polygon Amoy** | 80002 | https://rpc-amoy.polygon.technology | faucet.polygon.technology |
| **Arbitrum Sepolia** | 421614 | https://sepolia-rollup.arbitrum.io/rpc | faucet.arbitrum.io |
| **Base Sepolia** | 84532 | https://sepolia.base.org | faucet.quicknode.com/base/sepolia |
| **OP Sepolia** | 11155420 | https://sepolia.optimism.io | faucet.quicknode.com/optimism/sepolia |

## Free RPC Providers (No API Key Required)

| Provider | Chain Support | Rate Limit |
|--------|--------|---------|
| **LlamaRPC** | ETH/Polygon/Arb/Op | Generous |
| **PublicNode** | Multi-chain | Generous |
| **Infura Free** | ETH/Polygon | 100K req/day |
| **Alchemy Free** | ETH/Polygon/Arb | 300M compute/month |
| **QuickNode Free** | Multi-chain | 10M req/month |

## Non-EVM Chains

| Chain | Network | RPC/Endpoint | Explorer |
|----|------|-------------|---------|
| **Solana** | mainnet-beta | https://api.mainnet-beta.solana.com | solscan.io / explorer.solana.com |
| **Solana** | devnet | https://api.devnet.solana.com | — |
| **NEAR** | mainnet | https://rpc.mainnet.near.org | nearblocks.io |
| **NEAR** | testnet | https://rpc.testnet.near.org | — |
| **Cosmos Hub** | — | https://cosmos-rpc.publicnode.com:443 | mintscan.io |
| **Aptos** | mainnet | https://fullnode.mainnet.aptoslabs.com | explorer.aptoslabs.com |
| **Sui** | mainnet | https://fullnode.mainnet.sui.io | suiscan.xyz |

## wagmi/viem Chain Configuration
```typescript
import { mainnet, polygon, arbitrum, optimism, base, bsc, avalanche } from 'wagmi/chains'
// Import and use directly, no need to manually configure chainId
```

## viem Manual Custom Chain Configuration
```typescript
import { defineChain } from 'viem'
const myChain = defineChain({
  id: 12345, name: 'My Chain',
  nativeCurrency: { name: 'ETH', symbol: 'ETH', decimals: 18 },
  rpcUrls: { default: { http: ['https://my-rpc.com'] } },
  blockExplorers: { default: { name: 'Explorer', url: 'https://explorer.mychain.com' } },
})
```