Google Wallet offers pass issuers powerful and distinct ways to engage users through notifications, ensuring timely and relevant information reaches them directly on their mobile devices. Among these tools are,

Change Messages (Field Update Notifications)
Partner-Triggered Push Messages
Nearby Notifications

Terminology

Google Wallet

The mobile platform or system that offers pass issuers ways to engage users through notifications and allows users to save and manage passes (e.g., boarding passes, loyalty cards, offers).

Change Messages (Field Update Notifications)

A specific type of push notification automatically triggered by the Google Wallet system when a developer updates a critical, user-facing piece of data on a saved pass object via a standard API UPDATE or PATCH call.

Pass Issuer

The entity (developer/organisation) that creates and manages the digital passes (e.g., airlines, retailers, loyalty programs) using the Google Wallet API.

Partner-Triggered Push Messages

A text communication, often for marketing or service announcements, sent by the pass issuer, which triggers a push notification that directs the user to the back of the pass.

Nearby Notifications

A contextual reminder that the user has a relevant pass saved, delivered as a sticky notification, and triggered when a user's device enters a proximity zone around a physical location defined in the pass location settings.

Quota (for Partner-Triggered Messages)

A limit applied to prevent spam, restricting the issuer to a maximum of 3 messages that trigger a push notification per pass object within a 24-hour period.

What Are Change Messages (Field Update Notifications)?

In the context of the Google Wallet API, "Change Messages" refer to Field Update Notifications.

A Change Message is a specific type of push notification automatically triggered by the Google Wallet system when a developer updates a critical, user-facing piece of data on a saved pass object. They are designed to alert the user to a material change on their pass.

Purpose: To provide users with timely updates on the status or details of their pass, such as a gate change on a boarding pass or an increase in their loyalty point balance.
Mechanism: They are triggered during a standard API UPDATE or PATCH call on a pass object. The developer must include a specific transient field, often called notifyPreference: notifyOnUpdate, in the API request for the update to trigger a notification.

What Fields Trigger Change Messages?

Change Messages are triggered by updates to fields deemed important enough to warrant an immediate user notification. While the list can be extensive across different pass types (e.g., loyalty, offers, boarding passes), the key requirement is that the developer explicitly requests the notification during the update.

Common examples of fields that typically trigger a Change Message when updated with the notification preference include:

Pass Type	Example Fields That Trigger a Notification
Boarding Passes	Gate number, Seat assignment, or Flight status.
Loyalty/Gift Cards	Points balance, Tier status, or Account level.
Offers/Coupons	Expiration date or Offer details.

The granularity of these notifications means you can choose to trigger an alert specifically when a loyalty balance crosses a threshold, or a tier status is upgraded, making them highly user-centric and engaging.

How Change Messages Differ from Other Notifications

Change Messages are one of three main ways pass issuers can communicate with users, each with a distinct purpose and trigger mechanism.

Difference from Google Wallet Pass Push Messages (Partner-Triggered Messages)

Feature	Change Messages (Field Update Notifications)	Partner-Triggered Push Messages (Add Message and Notify)
What it is	An alert for an API data change on the pass object.	A text communication, often for marketing or service announcements.
Trigger	Updating a supported field	Using the `Add Message` API with `messageType: TEXT_AND\_NOTIFY`.
User Experience	A standard push notification alerting to a data update (e.g., "Your flight gate has changed").	A push notification that directs the user to the back of the pass where the new, highlighted message (often a longer text block) is displayed.
Content Control	The notification text is controlled by Google Wallet and is standard for the type of change.	The issuer provides the custom text for the message displayed on the back of the pass, which can contain relevant links.
Quota	No explicit mention of a separate quota, generally tied to the total update quota.	Limited to a maximum of 3 messages that trigger a push notification per pass object within a 24-hour period to prevent spam.

Difference from Nearby Notifications

Feature	Change Messages (Field Update Notifications)	Nearby Notifications
What it is	An alert for a data change on the pass object.	A contextual reminder that the user has a relevant pass saved based on their physical location.
Trigger	Updating a pass field.	A user's device entering a proximity zone around a location defined in the pass location settings (up to 10 locations per class/object).
User Experience	Delivered regardless of the user's location, based on an event.	Delivers a sticky notification (one that remains until the user leaves the area) that, when tapped, opens the pass for immediate use at the physical location.
Control	The issuer controls when the change happens.	Google Wallet determines the proximity range, the duration required in the area, and the text of the notification.
Prerequisites	User must have general pass notifications enabled.	User must have general pass notifications and precise, always-on location services enabled for Google Wallet.

Summary

If you need to inform a user about a fact-based update on their pass (like a gate change), use a Change Message. If you need to send a custom service or marketing text to the user, use a Partner-Triggered Push Message. And if you want to remind a user to use their pass when they are physically near your location, use a Nearby Notification.