Mollie

Developer-friendly & type-safe Csharp SDK specifically catered to leverage Mollie API.

Summary

Table of Contents

• Mollie
  • SDK Installation
  • SDK Example Usage
  • Authentication
  • Idempotency Key
  • Add Custom User-Agent Header
  • Add Profile ID and Testmode to Client
  • Available Resources and Operations
  • Global Parameters
  • Retries
  • Error Handling
  • Server Selection
  • Custom HTTP Client
• Development
  • Maturity
  • Contributions

SDK Installation

NuGet

To add the NuGet package to a .NET project:

dotnet add package Mollie

Locally

To add a reference to a local instance of the SDK in a .NET project:

dotnet add reference src/Mollie/Mollie.csproj

SDK Example Usage

Example

using Mollie;
using Mollie.Models.Components;
using Mollie.Models.Requests;

var sdk = new Client(
    testmode: false,
    security: new Security() {
        ApiKey = "<YOUR_BEARER_TOKEN_HERE>",
    }
);

ListBalancesRequest req = new ListBalancesRequest() {
    Currency = "EUR",
    From = "bal_gVMhHKqSSRYJyPsuoPNFH",
    Limit = 50,
    IdempotencyKey = "123e4567-e89b-12d3-a456-426",
};

var res = await sdk.Balances.ListAsync(req);

// handle response

Authentication

Per-Client Security Schemes

This SDK supports the following security schemes globally:

Name	Type	Scheme
ApiKey	http	HTTP Bearer
OAuth	oauth2	OAuth2 token

You can set the security parameters through the security optional parameter when initializing the SDK client instance. The selected scheme will be used by default to authenticate with the API for all operations that support it. For example:

using Mollie;
using Mollie.Models.Components;
using Mollie.Models.Requests;

var sdk = new Client(
    security: new Security() {
        ApiKey = "<YOUR_BEARER_TOKEN_HERE>",
    },
    testmode: false
);

ListBalancesRequest req = new ListBalancesRequest() {
    Currency = "EUR",
    From = "bal_gVMhHKqSSRYJyPsuoPNFH",
    Limit = 50,
    IdempotencyKey = "123e4567-e89b-12d3-a456-426",
};

var res = await sdk.Balances.ListAsync(req);

// handle response

Idempotency Key

This SDK supports the usage of Idempotency Keys. See our documentation on how to use it.

using Mollie;
using Mollie.Models.Components;
using Mollie.Models.Requests;
using System.Collections.Generic;

var sdk = new Mollie.Client(security: new Security() {
    ApiKey = Environment.GetEnvironmentVariable("MOLLIE_API_KEY") ?? "test_...",
});

var paymentRequest = new PaymentRequest() {
    Description = "Description",
    Amount = new Amount() {
        Currency = "EUR",
        Value = "5.00",
    },
    RedirectUrl = "https://example.org/redirect"
};

var idempotencyKey = "<some-idempotency-key>";

var payment1 = await sdk.Payments.CreateAsync(
    idempotencyKey: idempotencyKey,
    paymentRequest: paymentRequest
);

var payment2 = await sdk.Payments.CreateAsync(
    idempotencyKey: idempotencyKey,
    paymentRequest: paymentRequest
);

Console.WriteLine("Payment created with ID: " + payment1.PaymentResponse?.Id);
Console.WriteLine("Payment created with ID: " + payment2.PaymentResponse?.Id);
if (payment1.PaymentResponse?.Id == payment2.PaymentResponse?.Id) {
    Console.WriteLine("Payments are the same");
} else {
    Console.WriteLine("Payments are different");
}

Add Custom User-Agent Header

The SDK allows you to append a custom suffix to the User-Agent header for all requests. This can be used to identify your application or integration when interacting with the API, making it easier to track usage or debug requests. The suffix is automatically added to the default User-Agent string generated by the SDK. You can add it when creating the client:

var sdk = new Mollie.Client(
    security: new Security() {
        ApiKey = Environment.GetEnvironmentVariable("MOLLIE_API_KEY") ?? "test_...",
    },
    customUserAgent: "insert something here"
);

Add Profile ID and Testmode to Client

The SDK allows you to define the profileId and testmode in the client. This way, you don't need to add this information to the payload every time when using OAuth. This will not override the details provided in the individual requests.

var sdk = new Mollie.Client(
    security: new Security() {
        OAuth = Environment.GetEnvironmentVariable("MOLLIE_OAUTH_KEY") ?? "",
    },
    testmode: true,
    profileId: "pfl_..."
);

Available Resources and Operations

Available methods

Balances

• List - List balances
• Get - Get balance
• GetPrimary - Get primary balance
• GetReport - Get balance report
• ListTransactions - List balance transactions

BalanceTransfers

• Create - Create a Connect balance transfer
• List - List all Connect balance transfers
• Get - Get a Connect balance transfer

Capabilities

• List - List capabilities

Captures

• Create - Create capture
• List - List captures
• Get - Get capture

Chargebacks

• List - List payment chargebacks
• Get - Get payment chargeback
• All - List all chargebacks

ClientLinks

• Create - Create client link

Clients

• List - List clients
• Get - Get client

Customers

• Create - Create customer
• List - List customers
• Get - Get customer
• Update - Update customer
• Delete - Delete customer
• CreatePayment - Create customer payment
• ListPayments - List customer payments

DelayedRouting

• Create - Create a delayed route
• List - List payment routes

Invoices

• List - List invoices
• Get - Get invoice

Mandates

• Create - Create mandate
• List - List mandates
• Get - Get mandate
• Revoke - Revoke mandate

Methods

• List - List payment methods
• All - List all payment methods
• Get - Get payment method

Onboarding

• Get - Get onboarding status
• Submit - Submit onboarding data

Organizations

• Get - Get organization
• GetCurrent - Get current organization
• GetPartner - Get partner status

PaymentLinks

• Create - Create payment link
• List - List payment links
• Get - Get payment link
• Update - Update payment link
• Delete - Delete payment link
• ListPayments - Get payment link payments

Payments

• Create - Create payment
• List - List payments
• Get - Get payment
• Update - Update payment
• Cancel - Cancel payment
• ReleaseAuthorization - Release payment authorization

Permissions

• List - List permissions
• Get - Get permission

Profiles

• Create - Create profile
• List - List profiles
• Get - Get profile
• Update - Update profile
• Delete - Delete profile
• GetCurrent - Get current profile

Refunds

• Create - Create payment refund
• List - List payment refunds
• Get - Get payment refund
• Cancel - Cancel payment refund
• All - List all refunds

SalesInvoices

• Create - Create sales invoice
• List - List sales invoices
• Get - Get sales invoice
• Update - Update sales invoice
• Delete - Delete sales invoice

Settlements

• List - List settlements
• Get - Get settlement
• GetOpen - Get open settlement
• GetNext - Get next settlement
• ListPayments - List settlement payments
• ListCaptures - List settlement captures
• ListRefunds - List settlement refunds
• ListChargebacks - List settlement chargebacks

Subscriptions

• Create - Create subscription
• List - List customer subscriptions
• Get - Get subscription
• Update - Update subscription
• Cancel - Cancel subscription
• All - List all subscriptions
• ListPayments - List subscription payments

Terminals

• List - List terminals
• Get - Get terminal

Wallets

• RequestApplePaySession - Request Apple Pay payment session

WebhookEvents

• Get - Get a Webhook Event

Webhooks

• Create - Create a webhook
• List - List all webhooks
• Update - Update a webhook
• Get - Get a webhook
• Delete - Delete a webhook
• Test - Test a webhook

Global Parameters

Certain parameters are configured globally. These parameters may be set on the SDK client instance itself during initialization. When configured as an option during SDK initialization, These global values will be used as defaults on the operations that use them. When such operations are called, there is a place in each to override the global value, if needed.

For example, you can set profileId to `` at SDK initialization and then you do not have to pass the same value on calls to operations like List. But if you want to do so you may, which will locally override the global setting. See the example code below for a demonstration.

Available Globals

The following global parameters are available.

Name	Type	Description
profileId	string	The identifier referring to the profile you wish to retrieve the resources for. Most API credentials are linked to a single profile. In these cases the profileId can be omitted. For organization-level credentials such as OAuth access tokens however, the profileId parameter is required.
testmode	bool	Most API credentials are specifically created for either live mode or test mode. In those cases the testmode query parameter can be omitted. For organization-level credentials such as OAuth access tokens, you can enable test mode by setting the testmode query parameter to true. Test entities cannot be retrieved when the endpoint is set to live mode, and vice versa.
customUserAgent	string	Custom user agent string to be appended to the default Mollie SDK user agent.

Example

using Mollie;
using Mollie.Models.Components;
using Mollie.Models.Requests;

var sdk = new Client(
    testmode: false,
    profileId: "<id>",
    customUserAgent: "<value>",
    security: new Security() {
        ApiKey = "<YOUR_BEARER_TOKEN_HERE>",
    }
);

ListBalancesRequest req = new ListBalancesRequest() {
    Currency = "EUR",
    From = "bal_gVMhHKqSSRYJyPsuoPNFH",
    Limit = 50,
    IdempotencyKey = "123e4567-e89b-12d3-a456-426",
};

var res = await sdk.Balances.ListAsync(req);

// handle response

Retries

Some of the endpoints in this SDK support retries. If you use the SDK without any configuration, it will fall back to the default retry strategy provided by the API. However, the default retry strategy can be overridden on a per-operation basis, or across the entire SDK.

To change the default retry strategy for a single API call, simply pass a RetryConfig to the call:

using Mollie;
using Mollie.Models.Components;
using Mollie.Models.Requests;

var sdk = new Client(
    testmode: false,
    security: new Security() {
        ApiKey = "<YOUR_BEARER_TOKEN_HERE>",
    }
);

ListBalancesRequest req = new ListBalancesRequest() {
    Currency = "EUR",
    From = "bal_gVMhHKqSSRYJyPsuoPNFH",
    Limit = 50,
    IdempotencyKey = "123e4567-e89b-12d3-a456-426",
};

var res = await sdk.Balances.ListAsync(
    retryConfig: new RetryConfig(
        strategy: RetryConfig.RetryStrategy.BACKOFF,
        backoff: new BackoffStrategy(
            initialIntervalMs: 1L,
            maxIntervalMs: 50L,
            maxElapsedTimeMs: 100L,
            exponent: 1.1
        ),
        retryConnectionErrors: false
    ),
    request: req
);

// handle response

If you'd like to override the default retry strategy for all operations that support retries, you can use the RetryConfig optional parameter when intitializing the SDK:

using Mollie;
using Mollie.Models.Components;
using Mollie.Models.Requests;

var sdk = new Client(
    retryConfig: new RetryConfig(
        strategy: RetryConfig.RetryStrategy.BACKOFF,
        backoff: new BackoffStrategy(
            initialIntervalMs: 1L,
            maxIntervalMs: 50L,
            maxElapsedTimeMs: 100L,
            exponent: 1.1
        ),
        retryConnectionErrors: false
    ),
    testmode: false,
    security: new Security() {
        ApiKey = "<YOUR_BEARER_TOKEN_HERE>",
    }
);

ListBalancesRequest req = new ListBalancesRequest() {
    Currency = "EUR",
    From = "bal_gVMhHKqSSRYJyPsuoPNFH",
    Limit = 50,
    IdempotencyKey = "123e4567-e89b-12d3-a456-426",
};

var res = await sdk.Balances.ListAsync(req);

// handle response

Error Handling

BaseException is the base exception class for all HTTP error responses. It has the following properties:

Property	Type	Description
Message	string	Error message
Request	HttpRequestMessage	HTTP request object
Response	HttpResponseMessage	HTTP response object

Some exceptions in this SDK include an additional Payload field, which will contain deserialized custom error data when present. Possible exceptions are listed in the Error Classes section.

Example

using Mollie;
using Mollie.Models.Components;
using Mollie.Models.Errors;
using Mollie.Models.Requests;

var sdk = new Client(
    testmode: false,
    security: new Security() {
        ApiKey = "<YOUR_BEARER_TOKEN_HERE>",
    }
);

try
{
    ListBalancesRequest req = new ListBalancesRequest() {
        Currency = "EUR",
        From = "bal_gVMhHKqSSRYJyPsuoPNFH",
        Limit = 50,
        IdempotencyKey = "123e4567-e89b-12d3-a456-426",
    };

    var res = await sdk.Balances.ListAsync(req);

    // handle response
}
catch (BaseException ex)  // all SDK exceptions inherit from BaseException
{
    // ex.ToString() provides a detailed error message
    System.Console.WriteLine(ex);

    // Base exception fields
    HttpRequestMessage request = ex.Request;
    HttpResponseMessage response = ex.Response;
    var statusCode = (int)response.StatusCode;
    var responseBody = ex.Body;

    if (ex is ErrorResponse) // different exceptions may be thrown depending on the method
    {
        // Check error data fields
        ErrorResponsePayload payload = ex.Payload;
        long Status = payload.Status;
        string Title = payload.Title;
        // ...
    }

    // An underlying cause may be provided
    if (ex.InnerException != null)
    {
        Exception cause = ex.InnerException;
    }
}
catch (OperationCanceledException ex)
{
    // CancellationToken was cancelled
}
catch (System.Net.Http.HttpRequestException ex)
{
    // Check ex.InnerException for Network connectivity errors
}

Error Classes

Primary exceptions:

• BaseException: The base class for HTTP error responses.
  • ErrorResponse: An error response object. *

Less common exceptions (2)

• System.Net.Http.HttpRequestException: Network connectivity error. For more details about the underlying cause, inspect the ex.InnerException.

• Inheriting from BaseException:

  • ResponseValidationError: Thrown when the response data could not be deserialized into the expected type.

* Refer to the relevant documentation to determine whether an exception applies to a specific operation.

Server Selection

Override Server URL Per-Client

The default server can be overridden globally by passing a URL to the serverUrl: string optional parameter when initializing the SDK client instance. For example:

using Mollie;
using Mollie.Models.Components;
using Mollie.Models.Requests;

var sdk = new Client(
    serverUrl: "https://api.mollie.com/v2",
    testmode: false,
    security: new Security() {
        ApiKey = "<YOUR_BEARER_TOKEN_HERE>",
    }
);

ListBalancesRequest req = new ListBalancesRequest() {
    Currency = "EUR",
    From = "bal_gVMhHKqSSRYJyPsuoPNFH",
    Limit = 50,
    IdempotencyKey = "123e4567-e89b-12d3-a456-426",
};

var res = await sdk.Balances.ListAsync(req);

// handle response

Custom HTTP Client

The C# SDK makes API calls using an ISpeakeasyHttpClient that wraps the native HttpClient. This client provides the ability to attach hooks around the request lifecycle that can be used to modify the request or handle errors and response.

The ISpeakeasyHttpClient interface allows you to either use the default SpeakeasyHttpClient that comes with the SDK, or provide your own custom implementation with customized configuration such as custom message handlers, timeouts, connection pooling, and other HTTP client settings.

The following example shows how to create a custom HTTP client with request modification and error handling:

using Mollie;
using Mollie.Utils;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;

// Create a custom HTTP client
public class CustomHttpClient : ISpeakeasyHttpClient
{
    private readonly ISpeakeasyHttpClient _defaultClient;

    public CustomHttpClient()
    {
        _defaultClient = new SpeakeasyHttpClient();
    }

    public async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken? cancellationToken = null)
    {
        // Add custom header and timeout
        request.Headers.Add("x-custom-header", "custom value");
        request.Headers.Add("x-request-timeout", "30");
        
        try
        {
            var response = await _defaultClient.SendAsync(request, cancellationToken);
            // Log successful response
            Console.WriteLine($"Request successful: {response.StatusCode}");
            return response;
        }
        catch (Exception error)
        {
            // Log error
            Console.WriteLine($"Request failed: {error.Message}");
            throw;
        }
    }

    public void Dispose()
    {
        _httpClient?.Dispose();
        _defaultClient?.Dispose();
    }
}

// Use the custom HTTP client with the SDK
var customHttpClient = new CustomHttpClient();
var sdk = new Client(client: customHttpClient);

You can also provide a completely custom HTTP client with your own configuration:

using Mollie.Utils;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;

// Custom HTTP client with custom configuration
public class AdvancedHttpClient : ISpeakeasyHttpClient
{
    private readonly HttpClient _httpClient;

    public AdvancedHttpClient()
    {
        var handler = new HttpClientHandler()
        {
            MaxConnectionsPerServer = 10,
            // ServerCertificateCustomValidationCallback = customCertValidation, // Custom SSL validation if needed
        };

        _httpClient = new HttpClient(handler)
        {
            Timeout = TimeSpan.FromSeconds(30)
        };
    }

    public async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken? cancellationToken = null)
    {
        return await _httpClient.SendAsync(request, cancellationToken ?? CancellationToken.None);
    }

    public void Dispose()
    {
        _httpClient?.Dispose();
    }
}

var sdk = Client.Builder()
    .WithClient(new AdvancedHttpClient())
    .Build();

For simple debugging, you can enable request/response logging by implementing a custom client:

public class LoggingHttpClient : ISpeakeasyHttpClient
{
    private readonly ISpeakeasyHttpClient _innerClient;

    public LoggingHttpClient(ISpeakeasyHttpClient innerClient = null)
    {
        _innerClient = innerClient ?? new SpeakeasyHttpClient();
    }

    public async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken? cancellationToken = null)
    {
        // Log request
        Console.WriteLine($"Sending {request.Method} request to {request.RequestUri}");
        
        var response = await _innerClient.SendAsync(request, cancellationToken);
        
        // Log response
        Console.WriteLine($"Received {response.StatusCode} response");
        
        return response;
    }

    public void Dispose() => _innerClient?.Dispose();
}

var sdk = new Client(client: new LoggingHttpClient());

The SDK also provides built-in hook support through the SDKConfiguration.Hooks system, which automatically handles BeforeRequestAsync, AfterSuccessAsync, and AfterErrorAsync hooks for advanced request lifecycle management.

Development

Maturity

This SDK is in beta, and there may be breaking changes between versions without a major version update. Therefore, we recommend pinning usage to a specific package version. This way, you can install the same version each time without breaking changes unless you are intentionally looking for the latest version.

Contributions

While we value open-source contributions to this SDK, this library is generated programmatically. Any manual changes added to internal files will be overwritten on the next generation. We look forward to hearing your feedback. Feel free to open a PR or an issue with a proof of concept and we'll do our best to include it in a future release.

SDK Created by Speakeasy