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Make read-only requests

You can use the Infura API from your dapp with MetaMask SDK installed to make direct, read-only JSON-RPC requests.

Direct, read-only JSON-RPC requests are blockchain requests that do not require user wallet interaction. Your dapp can directly call most JSON-RPC API methods, bypassing user wallet authentication for read-only operations.

note

Your dapp cannot directly call the following RPC methods, which require user wallet interaction:

  • eth_requestAccounts
  • eth_sendTransaction
  • eth_signTransaction
  • eth_sign
  • eth_accounts
  • personal_sign
  • eth_signTypedData_v4
  • wallet_watchAsset
  • wallet_addEthereumChain
  • wallet_switchEthereumChain

Configure your dapp to make read-only requests using the Infura API, custom nodes, or both.

Prerequisites​

  • An Infura API key. Create one by following the first two steps in the Infura getting started guide.

  • An allowlist configured for your API key.

    important

    Your API key, when used with the SDK, is vulnerable to exposure. If someone inspects your dapp's code, they can potentially retrieve your API key and submit requests to Infura, impersonating your account.

    Use allowlists to protect against this vulnerability. You can restrict interactions with your API key to specific addresses, origins, user agents, and request methods. We recommend using all allowlist options to maximize the security of your API key and dapp.

  • MetaMask SDK set up in your JavaScript dapp.

Use the Infura API​

To use the Infura API to make read-only requests, specify your Infura API key using the infuraAPIKey option when instantiating the SDK in your dapp.

infuraAPIKey: "YOUR-API-KEY"

Use custom nodes​

To use your own node (for example, with Hardhat) to make read-only requests, specify your node's chain ID and RPC URL using the readonlyRPCMap option when instantiating the SDK in your dapp.

readonlyRPCMap: {
  "0x539": "http://localhost:8545",
}

In this example, chain ID 0x539 maps to the custom node's RPC URL.

Use the Infura API and custom nodes​

You can use both the Infura API and custom nodes to make read-only requests by specifying both the infuraAPIKey and readonlyRPCMap options when instantiating the SDK in your dapp.

sdkOptions={{
  infuraAPIKey: "YOUR-API-KEY",
  readonlyRPCMap: {
    "0x539": "http://localhost:8545",
  },
  // Other options.
}}

infuraAPIKey provides access to various networks supported by Infura, and readonlyRPCMap provides access to custom nodes. The readonlyRPCMap values override Infura networks in case of a conflict.

Refer to the SDK's default RPC URLs map to see how Infura networks are configured by default. By defining your own readonlyRPCMap, you can override these defaults or add support for other networks.

Example​

The following is an example of using both the Infura API and custom nodes with the SDK:

sdkOptions={{
  infuraAPIKey: "YOUR-API-KEY",
  readonlyRPCMap: {
    // Custom node.
    "0x539": "http://localhost:8545",
    // Override Infura Mainnet.
    "0x1": "https://mainnet.infura.io/v3/YOUR-API-KEY",
  },
  defaultReadOnlyChainId: "0x1",
  // Other options.
}}

In this example, read-only requests to Mainnet (chain ID 0x1) use the Infura API, while read-only requests to the local testnet (chain ID 0x539) use the custom node. defaultReadOnlyChainId enables making read-only requests before the user connects to MetaMask, and specifies to make those requests to Mainnet.