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This page explains how to configure your app so that it connects to supported networks, which include all EVM-compatible L1/L2 networks.

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Switching or adding alternative EVM-compatible chains

Coinbase Wallet SDK and Coinbase Wallet clients support both EIP-3326 wallet_switchEthereumChain and EIP-3085 wallet_addEthereumChain requests for switching networks. For apps supporting multiple networks, Coinbase Wallet SDK only needs 1 rpcUrl — the rpcUrl of the chain the app wishes to default users to. If Wallet SDK receives either a wallet_switchEthereumChain or wallet_addEthereumChain request for a whitelisted network then it switches the user to that network after asking approval from the user. Coinbase Wallet clients handle wallet_addEthereumChain requests for non-whitelisted networks (for example, a network such as Harmony One which is not currently supported by clients by default). An app can determine if a network is whitelisted or not by sending a wallet_switchEthereumChain request for that network. If error code 4092 is returned, then the network is not supported by default by the client wallet.

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Example

Here’s how to request the wallet switch networks: 
ethereum
  .request({
    method: "wallet_switchEthereumChain",
    params: [{ chainId: "0xA86A" }],
  })
  .then((response) => console.log(response));
Here’s how to request the client wallet add a new network 
ethereum
  .request({
    method: "wallet_addEthereumChain",
    params: [
      {
        chainId: "0x63564C40",
        rpcUrls: ["https://api.harmony.one"],
        chainName: "Harmony Mainnet",
        nativeCurrency: { name: "ONE", decimals: 18, symbol: "ONE" },
        blockExplorerUrls: ["https://explorer.harmony.one"],
        iconUrls: ["https://harmonynews.one/wp-content/uploads/2019/11/slfdjs.png"],
      },
    ],
  })
  .then((response) => console.log(response));
Many apps attempt to switch to a network with wallet_switchEthereumChain, determine if the network is supported by the wallet based on the error code, and follow with a wallet_addEthereumChain request if the network is not supported. Here’s an example: 
try {
  // attempt to switch to Harmony One network
  const result = await ethereum.send("wallet_switchEthereumChain", [{ chainId: `0x63564C40` }]);
} catch (switchError) {
  // 4902 indicates that the client does not recognize the Harmony One network
  if (switchError.code === 4902) {
    await ethereum.request({
      method: "wallet_addEthereumChain",
      params: [
        {
          chainId: "0x63564C40",
          rpcUrls: ["https://api.harmony.one"],
          chainName: "Harmony Mainnet",
          nativeCurrency: { name: "ONE", decimals: 18, symbol: "ONE" },
          blockExplorerUrls: ["https://explorer.harmony.one"],
          iconUrls: ["https://harmonynews.one/wp-content/uploads/2019/11/slfdjs.png"],
        },
      ],
    });
  }
}
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