Flutter SDK

Quick Start

Let's get started with Volume in less than 5 minutes.

Flutter for Volume is a library with custom view that allows you to display Volume checkout and start accepting payments from your customers in zero time into any flutter app.

Getting Started

Get started by installing Volume sdk.

        sdk: flutter
          url: https://<GIT_AUTHORIZATION>@github.com/getvolume/VolumePubDev.git
          ref: 1.8.0

Where GIT_AUTHORIZATION is environment variable made of github user and it's token volume-public:<token> in that manner. Token is provided by Volume.

e.g. volume-public:github_pat_72A4HWM8I0LwB3_T0kenProv1dedByV0lume__V3o9ZRvFBM5cmENW8vf8ES365KNJ7b6u7gY1

Volume Provider & Volume Button

The volume provider should be placed at the root level of your application, this provides key global configuration for using volume in your application. When VolumeProvider is initialized then you can add Volume button to your screen by adding VolumeButtonComponent to ExampleAppView struct.

import 'package:volume_sdk/volume_provider.dart';
void main() {
  const myApp = MyApp();
        applicationId: "", //provided by Volume
        volumeEnvironment: "sandbox",
        showSandboxBanks: true,
        maxPaymentAmount: "15000",
        minPaymentAmount: "1"),
        buttonCustomisation: const ButtonCustomization(),
        translations: {
          "EN": const VolumeTranslations(
              accountHolderNameText: "Name and Surname"),
          "DE": const VolumeTranslations(
              accountHolderNameText: "Name und Nachname"),
        language: "EN"),
  VolumeProvider.setLanguage("DE") // Use this to change language in runtime

You can use Volume widget by just declaring it in any Widget. To successfully initiate transaction you should set MerchantPaymentId, Reference and amount.

var merchantPaymentId = generateMerchantPaymentId();
  void initState() {
    _merchantPaymentIdController = TextEditingController(text: merchantPaymentId);
    _volumeButtonEventListener = VolumeButtonEventListener((value) {
      setState(() {
        merchantPaymentId = value;
  merchantPaymentId: merchantPaymentId, // Generate new value each time navigateToPaymentConsent event is emitted
  reference: "Example Reference", // Generate new reference value each time navigateToPaymentConsent event is emitted
  amount: 50.0,
  isEnabled: true,
  currency: "GBP",
  volumeEventListener: volumeButtonEventListener,
  metadata: <String, dynamic>{
      "type": "shirt",
      "color": "black",
      "owner": {
        "position": "CTO",
        "description": "Very handsome man",
        "details": {
          "name": "John",
          "surname": "Doe",
        "relatedItems": [
          { "itemName": "trousers", "color": "blue" },
          { "itemName": "shoes", "color": "white" },
String generateMerchantPaymentId()  {
  return "This should be unique value"; //TODO Get merchant Payment Id value from backend
class VolumeButtonEventListener implements VolumeEventListener {
  final void Function(dynamic value) onNavigateToPaymentConsent;
  const VolumeButtonEventListener(this.onNavigateToPaymentConsent );
  onEvent(VolumeEvent event) {
    switch (event.runtimeType) {
      case NavigateToPaymentConsent:


Expand the section below for a quick glance at what you need to know.

VolumeProvider properties

Required Properties

applicationIdString123456789Your Application Id as provided in your Merchant Portal. (Provided by Volume)
volumeEnvironmentStringsandboxEnvironment to be used, this is either 'live' | 'sandbox' | A full URI if we have provided a specific environment for you.

Optional Properties

volumeEventListenerVolumeEventListenerEventsEvent listener, object that reacts to Volume events, see Events for detailed instructions on how this works
showSandboxBanksBooleantrueFlag to enable showing sandbox banks. Used for testing
minPaymentAmountBigDecimal0.01 (default: 0.01)Minimum value for the amount field for each payment, when supplying a value smaller than this, a PAYMENT_AMOUNT_TOO_SMALL event will be emitted and the payment will not reach the volume api.
maxPaymentAmountBigDecimal15000 (default: 15000)Maximum value for the amount field for each payment, when supplying a value greater than this, a PAYMENT_AMOUNT_TOO_LARGE event will be emitted and the payment will not reach the volume api.
buttonCustomisationButtonCustomisationTweak the look and feel of the Volume button, properties to make changes to the colours, and border of the button.
translationsMap String to VolumeTranslationsMap of VolumeTranslations per language like "EN" or "DE". Allows to translate Volume component.
languageStringENSets the language to be used on Volume component.

For more information on Events with onEvent. Check out Events.

VolumePaymentView has following setters
amountBigDecimalMin 0.011Amount to be paid, ie £1.00.
currencyStringISO 4217GBPCurrency of payment
referenceString (Optional)Max 18 chars, AlphanumericABC-123Pass a bank transfer reference, it will be visible by both a client and merchant in bank transfer history.
merchantPaymentIdString (Optional)Max 50 chars, unique per payment123456Pass a merchantPaymentId to associate a unique identifier for the payment, this will be returned to you in any webhook or api responses for the given payment
isEnabledBooleantrueChanges the Enabled/Disabled state of the Volume button
metadataMap String to DynamicMax 5000 chars lengthmetadata is an optional JSON object which will be passed back in webhooks as paymentMetadata.
volumeEventListenerVolumeEventListenerEvent listener, object that reacts to Volume events, see Events for detailed instructions on how this works
paymentIdentifiersProviderPaymentIdentifiersProviderOptionalProvider for PaymentIdentifiers like MerchantPaymentId and Reference that are generatedPaymentIdentifiers on Merchant backend

Regenerating Merchant Payment ID

Each time VolumeEvent.NavigateToPaymentConsent is emitted Merchant Payment ID should be set to a new unique value.

Rendering Volume Button without MerchantPaymentId (Optional)

The PaymentIdentifiersProvider is an optional feature that allows merchants to provide a MerchantPaymentId and Reference fields when the user clicks the Volume Pay button. This enables the rendering of the Volume Button before creating a Payment entity on the merchant side.

providePaymentIdentifiers(): An asynchronous method that returns a Future<PaymentIdentifiers> object containing the payment identifiers.

class VolumePaymentIdentifiersProvider extends PaymentIdentifiersProvider {
  Future<PaymentIdentifiers> providePaymentIdentifiers() async {
    var generatedPaymentIdentifiers = // Get MerchantPaymentId and Reference from the backend
        PaymentIdentifiers(merchantPaymentId: generatedPaymentIdentifiers.merchantPaymentId, reference: generatedPaymentIdentifiers.reference);
    return paymentIdentifiers;
// Usage in the VolumePaymentButtonWidget
  merchantPaymentId: merchantPaymentId,
  reference: reference,
  amount: amount,
  currency: currency,
  isEnabled: isEnabled,
  volumeEventListener: _volumeButtonEventListener,
  paymentIdentifiersProvider: VolumePaymentIdentifiersProvider(),
  metadata: const <String, dynamic>{
    // ... metadata

❗When paymentIdentifiersProvider is provided then merchantPaymentId and reference fields values will be ignored and paymentIdentifiersProvider will be called each time user clicks on the Volume Button.

Implementing the after payment screen (Callback) in mobile app

Upon completion of the payment process, users are directed back from the banking app to your app using a callback via an app link or universal link. Volume accepts only https links, which means traditional deep links like myapp://callback are not supported. Instead, we recommend using App Links and Universal Links, such as https://myDomain.com/callback (opens in a new tab), for their superior security, user experience, seamless integration, and web fallback capabilities.


About app links (opens in a new tab)

Create Deep Links to App Content (opens in a new tab)


Supporting universal links in your iOS app (opens in a new tab)

Supporting associated domains on iOS (opens in a new tab)


Flutter app links library (opens in a new tab)

Universal links on Flutter (opens in a new tab)

React Native:

React Native linking documentation (opens in a new tab)

React Native app links tutorial (opens in a new tab)

Documentation for the Volume Callback parameters: Callback

iOS Banks detection required setup

To make bank detection work Apple require we add some values in your Info.plist to indicate intent to work with app schemes, we use this to detect which banking apps the end user has installed on their phone so that we can show them only banks they have installed.

To complete the setup there are some <string> tags we need to add under the LSApplicationQueriesSchemes key in Info.plist file.



After you have completed the steps above, then you can start testing.

We strongly recommend to use sandbox environment before switching to live environment.

Please note that sandbox testing will not open the Banking app due to lack of testing environment offered by the different banks in the UK. However, a successful test will open the bank environment via the browser. The user experience will differ bank by bank. Ask us more information at support@getvolume.com or use the chat in this page to get immediate assistance.

Please check Sandbox Banks Credentials to be able to test with Natwest Sandbox and other sandbox banks.