The Google Data Manager API, explained for conversion tracking

If you send offline conversions or first-party data to Google, you have probably used more than one API to do it. Customer Match lists went through the Google Ads API, server-side GA4 events went through the Measurement Protocol, Floodlight conversions went through Campaign Manager 360, and each had its own format and quirks. The Data Manager API is Google's move to put all of that behind a single connection.

This post covers what the Data Manager API is, how it sends conversion events to GA4 and Google Ads, how it compares to the methods it replaces, and what has changed in recent releases. It is a technical topic, but you do not need to be a developer to follow the shape of it.

What the Data Manager API is

The Data Manager API is a single ingestion API for sending first-party data to Google's advertising products. One connection can reach Google Ads, Google Analytics, Display & Video 360, Campaign Manager 360, Search Ads 360 and Google Ad Manager.

It handles two broad jobs. The first is audience data: Customer Match lists, mobile device IDs and PAIR IDs. The second, and the focus here, is conversion events: offline conversions, enhanced conversions for leads, and Google Analytics events. Both are sent to a small, shared set of endpoints rather than to a different system per product. It also supports confidential matching and encryption, so customer identifiers can be hashed and encrypted before they reach Google.

Sending conversion events to GA4 and Google Ads

For conversion tracking, the API covers the cases most advertisers care about.

For Google Ads you can send offline conversions, such as a lead that closed in your CRM, a phone sale or an in-store purchase, and enhanced conversions for leads, where a later conversion is matched back to an earlier ad click using hashed contact details. Store sales conversions are also supported for allowlisted accounts.

For Google Analytics you can send recommended and custom events server-to-server, and send a conversion with a transaction ID as an additional data source to strengthen an existing tag or Firebase event.

The detail that ties it together is destinations. A single request can carry more than one destination, so the same event can reach Google Ads and a Google Analytics property at once rather than being sent twice through separate integrations.

How this compares to the old way

Two older methods matter here.

For Google Analytics, server-side events have gone through the Measurement Protocol. Google has now placed the Measurement Protocol in a mature, finalised state. It is not deprecated and existing implementations keep working, but it will not receive new features, and Google points developers to the Data Manager API for new server-to-server integrations. Google's own comparison draws out four differences:

• Data model: the Data Manager API uses one model across all Google advertising products, where the Measurement Protocol is specific to Google Analytics.
• Encryption: the Data Manager API supports it, the Measurement Protocol does not.
• Destinations: the Data Manager API can send to multiple destinations in a single request, the Measurement Protocol sends to one data stream per request.
• API secret: the Data Manager API does not require one, the Measurement Protocol does.

For Google Ads, offline conversions have historically been uploaded through the Google Ads API. That still works, but the Data Manager API is the consolidated path going forward, and Google publishes upgrade guides with field mappings for moving offline conversions, Customer Match and Floodlight conversions across.

The practical read is that the older tools are not being switched off, but they are no longer where the development is happening. New features, such as encryption and multi-destination sends, are landing in the Data Manager API.

What you gain

The clearest benefit is consolidation. Instead of maintaining separate integrations for Customer Match, GA4 server events and Floodlight, you build once against one API. Google's data partner Treasure Data reported an 80% reduction in engineering effort after moving to it.

A few other points are worth noting. Encryption and confidential matching are built in. A single request can fan out to several Google products. And the audience targeting threshold has dropped to 100 members, down from 1,000, so smaller lists become usable. Google also frames the API as the way to feed first-party data into its AI-driven bidding, citing that marketers who have integrated AI tools deeply report 60% greater revenue growth than their peers. That figure is Google's, so read it as directional rather than a guarantee.

What's changed recently

The API has moved quickly, and the releases that matter for conversion tracking are easy to follow:

• v1.1 (June 2025): introduced the method for sending events.
• v1.2 (August 2025): added offline conversions and enhanced conversions for leads to Google Ads, plus event source values (APP, IN_STORE, PHONE, OTHER).
• v1.3 (October 2025): general availability for all users, request status diagnostics, and the lower 100-member audience threshold.
• v1.4 (November 2025): added Google Analytics purchase events as an additional data source, and support for AWS KMS encryption keys.
• v1.5 (February 2026): added full user list management, so audiences can be created, updated and deleted through the API as well as populated.
• v1.6 (May 2026): added Google Ads store sales conversions, and support for sending any non-reserved web or app event to Google Analytics.
• v1.7 (May 2026): added offline conversion events for Google Marketing Platform products (Campaign Manager 360, Search Ads 360 and Display & Video 360) through Floodlight, plus a conversion count field for tracking quantities.

A couple of details to flag. Sending Google Analytics conversions as an additional data source is generally available for Google Ads accounts, but still allowlist-only for Google Analytics properties. And since April 2026, accounts must self-declare whether their ads are political under the EU Political Ads Regulation, or certain operations can fail. Check both before planning around them.

Should you migrate now

If you are starting a new server-side or offline conversion integration, building it on the Data Manager API is the sensible default. There is little reason to invest in the Measurement Protocol or scattered Google Ads API uploads for new work when the supported path is clear.

If you already have working integrations, there is no switch-off date to rush for, but the direction is set. A reasonable approach is to leave stable systems in place, point new work at the Data Manager API, and plan a migration for anything you would otherwise be extending.

If you want help scoping that migration, or setting up conversion tracking through the Data Manager API, that is the kind of work we do at DATA HIT. Get in touch.