eth_url_parser

A Dart library for parsing and building Ethereum URLs according to ERC-681.

Originally translated from the JavaScript eth-url-parser package.

Features

• Strict EIP-681 grammar: only the spec-defined pay- prefix, addresses of exactly 40 hex digits, bare ENS targets (ethereum:vitalik.eth)
• Exact amount handling via BigInt — no precision loss at any magnitude, in either direction (parse or build)
• Parse Ethereum URIs into strongly-typed TransactionRequest objects
• Build valid Ethereum URIs from TransactionRequest objects
• Supports ERC-681 parameters: value, gas, gasLimit, gasPrice
• Supports ERC-20 transfer function calls
• Chain ID support
• All malformed input throws FormatException with a descriptive message
• No code generation required -- pure Dart

Installation

Add to your pubspec.yaml:

dependencies:
  eth_url_parser: ^0.2.0

Usage

Parsing an Ethereum URL

import 'package:eth_url_parser/eth_url_parser.dart';

final request = EthUrlParser.parse(
  'ethereum:0x1234DEADBEEF5678ABCD1234DEADBEEF5678ABCD?value=2.014e18&gas=45000',
);
print(request.targetAddress); // 0x1234DEADBEEF5678ABCD1234DEADBEEF5678ABCD
print(request.parameters['value']); // 2014000000000000000
print(request.parameters['gas']); // 45000

Building an Ethereum URL

import 'package:eth_url_parser/eth_url_parser.dart';

final uri = EthUrlParser.build(
  TransactionRequest(
    targetAddress: '0x1234DEADBEEF5678ABCD1234DEADBEEF5678ABCD',
    functionName: 'transfer',
    parameters: {
      'address': '0x8e23ee67d1332ad560396262c48ffbb01f93d052',
      'uint256': '1',
    },
  ),
);
print(uri);
// ethereum:0x1234DEADBEEF5678ABCD1234DEADBEEF5678ABCD/transfer?address=0x8e23ee67d1332ad560396262c48ffbb01f93d052&uint256=1

The TransactionRequest model

TransactionRequest(
  scheme: 'ethereum',       // default
  targetAddress: '0x...',   // required
  functionName: 'transfer', // optional
  prefix: 'pay',           // optional ('pay' is the only EIP-681 prefix)
  chainId: 1,              // optional
  parameters: {             // optional
    'value': '1000000000000000000',
    'gas': '21000',
  },
)

API Reference

EthUrlParser.parse(String uri)

Parses an Ethereum URI string and returns a TransactionRequest. Throws a FormatException for invalid URIs.

EthUrlParser.build(TransactionRequest request)

Builds an Ethereum URI string from a TransactionRequest object. Amounts with at least three trailing zeros are emitted in the exponent notation the EIP suggests (2.014e18); all others stay plain decimal, so round-trips never lose a wei. Throws a FormatException for an invalid prefix, target address, or amount.