> ## Documentation Index
> Fetch the complete documentation index at: https://developers.dwolla.com/llms.txt
> Use this file to discover all available pages before exploring further.
# C#
> `Dwolla.Client` is available on [Nuget](https://www.nuget.org/packages/Dwolla.Client/) with [source code](https://github.com/Dwolla/dwolla-v2-csharp) available on our GitHub page.
## Getting Started
### Installation
To begin using this SDK, you will first need to download it to your machine. We use [NuGet](https://www.nuget.org/packages/Dwolla.Client) to distribute this package. Check out the [Microsoft](https://docs.microsoft.com/en-us/nuget/consume-packages/install-use-packages-visual-studio) documentation for more information on how to install and manage packages from Nuget using Visual Studio.
Here's an example using the [Package Manager Console](https://docs.microsoft.com/en-us/nuget/consume-packages/install-use-packages-powershell?view=vsmac-2022)
```shell Shell theme={"dark"}
$ Install-Package Dwolla.Client -Version 5.2.2
```
### Initialization
Before any API requests can be made, you must first determine which environment you will be using, as well as fetch the application key and secret. To fetch your application key and secret, please visit one of the following links:
Finally, you can create an instance of `DwollaClient` by specifying which environment you will be using—Production or Sandbox—via the `isSandbox` boolean flag.
```csharp csharp theme={"dark"}
var client = DwollaClient.Create(isSandbox: true);
```
#### Tokens
Application access tokens are used to authenticate against the API on behalf of an application. Application tokens can be used to access resources in the API that either belong to the application itself (`webhooks`, `events`, `webhook-subscriptions`) or the Dwolla Account that owns the application (`accounts`, `customers`, `funding-sources`, etc.). Application tokens are obtained by using the [`client_credentials`](https://tools.ietf.org/html/rfc6749#section-4.4) OAuth grant type:
```csharp csharp theme={"dark"}
var tokenRes = await client.PostAuthAsync(
new Uri($"{client.AuthBaseAddress}/token"),
new AppTokenRequest {Key = "...", Secret = "..."});
```
*Application access tokens are short-lived: 1 hour. They do not include a `refresh_token`. When it expires, generate a new one using `AppTokenRequest`.*
## Making Requests
Once you've created a `DwollaClient`, currently, you can make low-level HTTP requests.
### Low-Level Requests
To make low-level HTTP requests, you can use the `GetAsync()`, `PostAsync()`, `UploadAsync()` and `DeleteAsync()` methods with the available [request models](https://github.com/Dwolla/dwolla-v2-csharp/blob/main/Dwolla.Client/Models/Requests). These methods will return responses that can be mapped to one of the available [response models](https://github.com/Dwolla/dwolla-v2-csharp/blob/main/Dwolla.Client/Models/Responses).
#### Setting Headers
To specify headers for a request (e.g., `Authorization`), you can pass a `Headers` object as the last argument.
```csharp csharp theme={"dark"}
var headers = new Headers {{"Authorization", $"Bearer {tokenRes.Content.Token}"}};
client.GetAsync(url, headers);
```
#### `GET`
```csharp csharp theme={"dark"}
// GET api.dwolla.com/customers
var url = new Uri("https://api.dwolla.com/customers");
client.GetAsync(url);
```
#### `POST`
```csharp csharp theme={"dark"}
// POST api.dwolla.com/customers
var url = new Uri("https://api.dwolla.com/customers/");
var request = new CreateCustomerRequest
{
FirstName = "Jane",
LastName = "Doe",
Email = "jane.doe@email.com"
};
var res = await PostAsync(url, request, headers);
//res.Response.Headers.Location => "https://api-sandbox.dwolla.com/customers/fc451a7a-ae30-4404-aB95-e3553fcd733f
// POST api.dwolla.com/customers/{id}/documents multipart/form-data foo=...
var url = new Uri("https://api-sandbox.dwolla.com/customers/{id}/documents");
var request = new UploadDocumentRequest
{
DocumentType = "idCard",
Document = new File
{
ContentType = "image/png",
Filename = "filename.jpg",
Stream = fileStream
}
};
client.UploadAsync(url, request, headers);
```
#### `DELETE`
```csharp csharp theme={"dark"}
// DELETE api.dwolla.com/resource
var url = "https://api.dwolla.com/labels/{id}"
client.DeleteAsync