UniRate Dart Client

Official Dart client for the UniRate API — free, real-time and historical currency exchange rates plus VAT rates. Works in Dart and Flutter (mobile, web, desktop).

• 🔄 Real-time exchange rates between 170+ currencies (fiat + crypto)
• 📈 Historical rates back to 1999
• ⏰ Time-series ranges up to 5 years
• 💰 Currency conversion (current and historical)
• 🏛️ VAT rates for countries worldwide
• 🆓 Free tier, no credit card required
• ⚡ Modern Dart: async/await, typed models, injectable http.Client
• 📦 One dependency — package:http

Requirements

• Dart SDK 3.0+ (or Flutter 3.10+)

Installation

dart pub add unirate_api

Or add it to your pubspec.yaml:

dependencies:
  unirate_api: ^0.1.0

Quick start

import 'package:unirate_api/unirate_api.dart';

Future<void> main() async {
  final client = UniRateClient('your-api-key');

  // Current rate
  final rate = await client.getRate(from: 'USD', to: 'EUR');
  print('USD -> EUR: $rate');

  // Convert
  final euros = await client.convert(amount: 100, from: 'USD', to: 'EUR');
  print('100 USD = $euros EUR');

  // All supported currencies
  final currencies = await client.getSupportedCurrencies();
  print('${currencies.length} currencies supported');

  client.close();
}

Get a free API key at https://unirateapi.com.

API

Current rates

// Single pair
final double rate = await client.getRate(from: 'USD', to: 'EUR');

// All rates for a base
final Map<String, double> rates = await client.getAllRates(from: 'USD');

// Convert an amount
final double result = await client.convert(amount: 100, from: 'USD', to: 'EUR');

// Supported currency list
final List<String> codes = await client.getSupportedCurrencies();

Historical data

// Rate on a specific date
final rate = await client.getHistoricalRate(date: '2024-01-01', from: 'USD', to: 'EUR');

// All rates on a date
final rates = await client.getHistoricalRates(date: '2024-01-01', from: 'USD');

// Convert using a historical rate
final amount = await client.convertHistorical(
  amount: 100,
  from: 'USD',
  to: 'EUR',
  date: '2024-01-01',
);

// Time series
final series = await client.getTimeSeries(
  startDate: '2024-01-01',
  endDate: '2024-01-07',
  base: 'USD',
  currencies: ['EUR', 'GBP'],
);

// Available historical coverage per currency
final limits = await client.getHistoricalLimits();

Historical endpoints require a Pro subscription and return ApiException (status 403) on the free tier.

VAT rates

// All countries
final vatRates = await client.getVatRates();

// Single country (ISO-3166 alpha-2 code)
final germany = await client.getVatRate(country: 'DE');
print('Germany VAT: ${germany.vatData.vatRate}%');

Error handling

Every method throws a subclass of UniRateException:

try {
  final rate = await client.getRate(from: 'USD', to: 'ZZZ');
} on AuthenticationException {
  // invalid API key
} on InvalidCurrencyException {
  // unknown currency code
} on RateLimitException {
  // back off and retry
} on InvalidDateException {
  // bad request parameters / date format
} on ApiException catch (e) {
  // other HTTP error — e.statusCode / e.response
} on UniRateException catch (e) {
  // network or decoding failure
}

Testing — inject a mock client

The constructor accepts any http.Client, so mocking is trivial with package:http's MockClient:

import 'package:http/testing.dart';
import 'package:http/http.dart' as http;
import 'package:unirate_api/unirate_api.dart';

final mock = MockClient((request) async => http.Response('{"rate": "0.92"}', 200));
final client = UniRateClient('test-key', httpClient: mock);

final rate = await client.getRate(from: 'USD', to: 'EUR'); // 0.92

When you supply your own client you own its lifecycle; close() only disposes a client the constructor created.

Rate limits

• Currency endpoints: standard rate limits apply
• Historical endpoints: 50 requests/hour on the free tier
• VAT endpoints: 1800 requests/hour on the free tier

Related clients

• unirate-api-python — Python (PyPI: unirate-api)
• unirate-api-nodejs — Node.js / TypeScript (npm: unirate-api)
• unirate-api-swift — Swift (SPM)
• unirate-api-java — Java (Maven)
• unirate-api-go — Go
• unirate-api-rust — Rust (crates.io: unirate-api)
• unirate-api-ruby — Ruby (gem: unirate-api)
• unirate-api-php — PHP (Composer: unirate-api/unirate-api)
• unirate-api-dotnet — .NET / C# (NuGet: UniRateApi)

License

MIT — see LICENSE.