What Postman is and why you should use it
Postman, is a powerful tool for testing calls to the Dwolla API. Whether you are new to Dwolla, want to explore the API, or are deep into your Dwolla integration debugging requests, Postman offers a simple interface to quickly consume the API. It’s my go-to app, I even use it on a daily basis when working with external developers!
One common issue I debug with developers is malformed requests. Whether it’s a mis-typed request parameter or you aren’t passing in the correct headers for the request, small issues like these can seriously delay the integration process.
With this in mind, I decided to put together a Postman collection— essentially a templated series of all requests in the API pointing towards our Sandbox environment. My hope is that you will find this collection useful in improving your development workflow efficiency. Read on for more info on getting set up with Postman and using the collection…
Setting up Postman and importing the Dwolla API v2 collection
To get started, make sure you have the Postman app downloaded. Once you’re all set up with Postman, click the button below which will prompt you to open Postman and import the collection.
The collection—“Dwolla API - Sandbox”—will show up in the left-side pane. Here you’ll see folders corresponding to resources in the API.
Before you can start submitting requests you’ll need to configure a few variables within Postman, such as a the “client_id” and the “client_secret” which are used to authenticate against the API.
Configuring Collection variables
The collection is preconfigured to use collection variables that look like this: {{variableName}}. In order to get up and running with the Collection, you’ll want to set values for the client_id and client_secret collection variables.
To edit collection variables, click on “View more actions” on the collection in the left side nav. You’ll then click “Edit” which will open a tab to edit variables.
The collection will be preconfigured with initial variables. You’ll want to set values for both client_id and client_secret and click save prior to submitting any requests in the collection. (More information below 
on where to obtain your client_id and client_secret)
Where do you obtain your client_id and client_secret?
The “client_id” and “client_secret” correspond with your Application “key” and “secret” which can be found within the Applications tab in your Dashboard. These client credentials will be used to generate an OAuth application access token, which is issued to the created application, via a pre-request script that runs before each request in the collection. The generated token string is then saved as the “appToken” value in your Postman environment to be used to obtain access to protected resources (e.g. Transfers, Funding Sources, Customers etc.) in the Dwolla API.
Now that you have your client credentials set, click save and you’re ready to start calling the API.
Using the collection
It is recommended to start out by calling the root of the API to fetch your accountId; this should then be updated as a collection/environment variable value. New environment variables such as transferId, masspaymentId, and customerId should then be set once these resources are created in the API.
The screenshot below shows fetching an Account’s list of funding sources. You’ll notice and inspect a few things when you select a request within the collection on the left sidebar: 1) a description of the endpoint you’re calling as well as required and optional parameters. 2) the request URL 3) the required headers and 4) a sample request body if it’s a POST request.
After clicking the blue “Send” button, you should then get a response back from the API allowing you to inspect: the response body (if applicable), response headers, and HTTP status code. Viewing sample JSON POST bodies provided in this collection will hopefully give you, as the developer, a point of reference as to what a request should look like.
Comfortable with using cURL to send requests to the API through the CLI or another language like Python? Postman contains a handy “Generate Code” button that allows to to see what the request looks like in a different language.
Questions about using Postman or have suggestions on improving the provided collection? Please don’t hesitate to reach out—we’re here to help!
