flutter_web3_webview

A Flutter WebView widget that lets in-app web pages talk to a Web3 wallet. It injects a provider bridge into every page so DApps can connect and request signatures over EIP-1193 (EVM) and the Solana wallet standard, while your Dart code stays in control of accounts, chains, and every signing prompt. Built on top of flutter_inappwebview.

Features

• Injects window.ethereum (EIP-1193 + EIP-6963) and a Solana wallet-standard provider (window.fxwallet) before page scripts run.
• Routes every wallet request to your Dart callbacks — you decide what to approve, sign, and return.
• EVM: eth_requestAccounts, eth_accounts, eth_chainId, personal_sign, eth_sign, eth_signTypedData (v3 / v4), eth_sendTransaction, wallet_switchEthereumChain / wallet_addEthereumChain.
• Solana: connect (solana_account), solana_signMessage, solana_signTransaction (serialised so concurrent requests are approved one at a time).
• Push wallet-side changes back into the page: chain and account switches emit chainChanged / accountsChanged to listening DApps.
• Optional MetaMask impersonation (window.ethereum.isMetaMask) for DApps that gate on it — off by default.
• A drop-in superset of InAppWebView: every flutter_inappwebview callback is forwarded through.

Installation

dependencies:
  flutter_web3_webview: ^1.0.0

Usage

Load the injected provider asset once (e.g. in main), then drop a Web3Webview into your widget tree and wire the wallet callbacks:

import 'package:flutter_web3_webview/flutter_web3_webview.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Web3Webview.initJs(); // load the provider bundle once
  runApp(const MyApp());
}

Web3Webview(
  initialUrlRequest: URLRequest(url: WebUri('https://app.uniswap.org')),
  settings: Web3Settings(
    name: 'My Wallet',
    eth: Web3EthSettings(
      chainId: 1,
      // Report window.ethereum.isMetaMask === true for DApps that require it.
      overwriteMetamask: false,
    ),
  ),

  // EVM ------------------------------------------------------------------
  ethAccounts: () async => ['0xYourAddress'],
  ethChainId: () async => 1,
  ethPersonalSign: (message) async => wallet.personalSign(message),
  ethSignTypedData: (json) async => wallet.signTypedDataV4(json),
  ethSendTransaction: (tx) async => wallet.sendTransaction(tx),
  walletSwitchEthereumChain: (chain) async {
    // Return true to accept the switch, false to reject (DApp sees 4001).
    return askUserToSwitch(chain);
  },
  walletAddEthereumChain: (chain) async {
    // EIP-3085: register the chain and return true; it resolves with null
    // and does NOT auto-switch. With no add handler the dispatcher rejects
    // the add with 4200 (unsupported method) rather than switching.
    return askUserToAddChain(chain);
  },

  // Solana ---------------------------------------------------------------
  solAccount: () async => 'YourBase58SolanaAddress',
  solSignMessage: (data) async => wallet.solSignMessage(data),
  solSignTransaction: (data) async => wallet.solSignTransaction(data),
)

Returning a value resolves the DApp's request; throwing rejects it. To surface a real wallet rejection, throw an error whose toString() carries the EIP-1193 4001 shape.

Wallet callbacks

Example

A full end-to-end demo — exercising every callback against real DApps, with real signing — lives at examples/web3_webview_demo.

License

MIT — see LICENSE.