# Transaction Footprint Notification
source: https://developer.mastercard.com/carbon-calculator/documentation/use-cases/txn_footprint_notification/index.md

The **Transaction Footprint Notification** service notifies the issuer with a transaction footprint in near real-time for a payment transaction that has recently been completed by a consumer. This allows the issuer to notify the consumers in near real-time about the carbon score of their recent transaction, thus providing a better user experience.

## Pre-requisites {#pre-requisites}

Following are the pre-requisites for the issuer to use this service:

1. A payment card should be enrolled under the issuer.
2. The issuer has implemented the **{host}** `/payment-cards/transaction-footprints/notifications` service.
3. The issuer has to share the **{host}** to their Mastercard representative for configuring the host in Carbon Calculator. This is a mandatory step to ensure successfully invoking the **{host}** `/payment-cards/transaction-footprints/notifications` URL.

Tip:   

1. **{host}** : it will be an issuer's hosting URL. For example `https://www.issuerbank.com`

<br />

2. To create your project on Mastercard Developers, refer to the [Before You Start](https://developer.mastercard.com/carbon-calculator/documentation/index.md#before-you-start) section for more information.
Note: Transaction Footprint Notification service is a default opt-in service, but the issuer needs to be onboarded to it first.

## Sequence Diagram {#sequence-diagram}

The following sequence diagram shows the order of events for a solution that uses the `/payment-cards/transaction-footprints/notifications` endpoint.

Diagram notify-consumer

**Following are the execution steps:**

1. The consumer makes a payment to the merchant for the purchase.
2. The merchant sends the transaction authorization request to Mastercard Switch via acquirer.
3. The Mastercard Switch processes the transaction and sends the authorization response back.
4. The Carbon Calculator application receives the authorization transaction data in real-time.
5. The application calculates the transaction footprint corresponding to the authorization transaction.
6. The issuer server sends the transaction footprint to the issuer app.
7. The issuer app notifies the consumer in near real-time, either through push notification or in-app messaging.

<br />

You will receive an error response for an invalid request or any missing request parameter. Note:   

* For more information about the error codes, refer to [Code and Formats](https://developer.mastercard.com/carbon-calculator/documentation/code-and-formats/index.md).
* Authorized and cleared transactions can be matched using Bank net reference number and Bank net reference date but with an accuracy of 95%. We may not always have a 1:1 mapping between the authorized and cleared transactions.

## Endpoint {#endpoint}


API Specification: `https://static.developer.mastercard.com/content/carbon-calculator/swagger/notify-transaction-service.yaml`