JIT Funding automates the loading of funds into accounts in real time during the transaction process. In a Gateway JIT Funding setup, the Marqeta platform and your system both participate in authorization decisions. Funds are drawn from the program gateway funding source defined by the card product.

The Marqeta platform and your system exchange messages of the following types:

For more information about JIT Funding, see About Just-in-Time Funding.

A program gateway funding source represents a bank account from which funds are drawn for JIT-funded transactions. In the sandbox environment, you can create a program gateway funding source that simulates funds for your test transactions. In a production environment, you must work with a Marqeta representative to define the bank account from which the program gateway funding source draws funds.

For a complete description of the

endpoint, see Program Gateway Funding Sources.

A card product defines attributes and behaviors for a set of cards. Each card product has a single funding source, which funds all transactions conducted using an associated card. Gateway JIT Funding setups require you to create a card product associated with a program gateway funding source.

For a complete description of the

endpoint, see Card Products.

To participate in Gateway JIT Funding decisions, your system must respond to requests sent by the Marqeta platform. Your system can respond to a funding request in the following ways:

For more information on handling Gateway JIT Funding events, see Gateway JIT Funding Messages.

To handle informative Gateway JIT Funding messages, your system must include an endpoint for receiving event notifications. Within seconds of each transaction, the Marqeta platform sends webhook notifications to your endpoint to enable you to track requests, maintain balances, and resolve timeout issues.

Your system must respond to each informative JIT Funding request using the

HTTP response code. If your system does not respond with the HTTP response code, the Marqeta platform will try to resend the message. For more information about the Marqeta platform webhook system, see About Webhooks.

In a production environment, a Gateway JIT Funding setup requires your system to have two endpoints configured: one to act as a gateway and participate in JIT Funding requests, and another to receive notifications. This tutorial, however, does not require you to set up endpoints on your system.

To create a mock gateway endpoint, go to https://beeceptor.com/ (or another mock endpoint service) and create a mock endpoint. Save the mock endpoint’s URL for use in later steps.

For more information on JIT Funding messages, see Gateway JIT Funding Messages.

To define the bank account from which funds are drawn for transactions, create a program gateway funding source.

Send a

request to the endpoint to create a new program gateway funding source.

Populate the

and fields with values of your choice. The must contain 20 to 50 characters, with at least one uppercase letter, one lowercase letter, one number, and one symbol. In a production environment, you would use the credentials for your environment. (Neither the username or password will be reused later in the tutorial.)

To define attributes and behaviors for a set of cards, create a card product. The

object defines the funding source associated with the card product.

Send a

request to the endpoint to create a new card product. Use the program gateway funding source you created in this tutorial.

Before you create a new card, you must create a user who will own the card.

Send a

request to the endpoint to create a new user.

Send a

request to the endpoint to create a new card. Use the card product and user tokens you created in this tutorial.

Now that you have created a card, you can use it to simulate a transaction.

Send the following

request to to simulate a transaction. Use the card token and mock endpoint you created in this tutorial.

Go to your mock endpoint URL. It should receive two messages. The first message contains the JIT Funding request. The second message contains the notification sent after the funding decision is made. Because you cannot reply to the JIT Funding request using your mock endpoint, the JIT Funding attempt fails no matter what. For the purposes of this scenario, you can ignore the second message.

The following is a snippet of the JIT Funding request.

In a production environment, your gateway endpoint programmatically returns a JIT Funding response and approves or denies the funding request.

A complete JIT Funding response includes the following elements:

The following is a sample JIT Funding response.

For the purposes of this scenario, continue to the next step.

For more information, see Using AVS with JIT Funding.

After your gateway responds to a JIT Funding request, the Marqeta platform sends a JIT Funding notification to your endpoint—your mock endpoint should have received this notification in Step 7. In a production environment, your system would use this data to update your ledger and ensure that the transaction concluded appropriately.

A JIT Funding notification contains two transaction messages:

For more information on transaction types, see Event Types.

For this scenario, review the notification to ensure that the Marqeta platform properly handled your JIT Funding response. An approved transaction notification with funding approved by your gateway looks like the following: