flutter_web3_webview 1.1.1

A Flutter WebView widget that bridges in-app web pages to a Web3 wallet over EIP-1193 (EVM) and the Solana wallet standard.

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: ^1.1.1

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 name and icons

Web3Settings.name sets the display name for both EIP-6963 and Solana Wallet Standard. EVM and Solana icons are configured independently; set both if they should use the same logo.

Icons must be complete image data URIs, such as data:image/png;base64,... or data:image/svg+xml;base64,.... Encode your image bytes instead of passing a Flutter asset path:

import 'dart:convert';
import 'package:flutter/services.dart';
import 'package:flutter_web3_webview/flutter_web3_webview.dart';

Future<Web3Settings> loadWalletSettings() async {
  final logo = await rootBundle.load('assets/wallet_logo.png');
  final logoBytes = logo.buffer.asUint8List(logo.offsetInBytes, logo.lengthInBytes);
  final logoDataUri = 'data:image/png;base64,${base64Encode(logoBytes)}';

  return Web3Settings(
    name: 'My Wallet',
    eth: Web3EthSettings(
      icon: logoDataUri,
      rdns: 'com.example.wallet',
    ),
    sol: Web3SolSettings(
      icon: logoDataUri,
    ),
  );
}

Declare the logo in your app's Flutter assets. After initializing the Flutter binding, await loadWalletSettings() and pass the result to Web3Webview.settings before creating the WebView.

When omitted, the display name defaults to Web3Wallet, each icon defaults to the built-in FxWallet icon, and the EVM reverse-DNS identifier defaults to io.web3wallet. Host apps should supply their own name, icons, and reverse-DNS identifier.

Wallet callbacks

Callback	Triggered by	Returns
ethAccounts	eth_requestAccounts / eth_accounts	List<String> of addresses
ethChainId	eth_chainId	chain id as int
ethPersonalSign	personal_sign	signature hex
ethSign	eth_sign	signature hex
ethSignTypedData	eth_signTypedData / _v3 / _v4	signature hex
ethSendTransaction	eth_sendTransaction	transaction hash
walletSwitchEthereumChain	wallet_switchEthereumChain	bool accept / reject
walletAddEthereumChain	wallet_addEthereumChain	bool accept / reject — if unset, add is rejected with 4200 (unsupported method)
solAccount	Solana connect	base58 address
solSignMessage	solana_signMessage	signature (hex)
solSignTransaction	solana_signTransaction	signature (base58)
onDefaultCallback	any other method	anything (or throw)

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.