Microsoft Advertising Launches Conversions API: What's New Beyond UET and Offline Tracking

In August 2026, Microsoft Advertising introduced Conversions API (CAPI), a new tool for server-side conversion data transmission designed to improve the accuracy of advertising analytics and reduce dependence on browser-based tracking.

Microsoft Ads previously allowed advertisers to send conversions through an API. However, the new CAPI combines the tracking of website events, CRM events, offline sales, and mobile applications into a single system.

Let's examine how the new tool differs from Universal Event Tracking (UET), what has become available to advertisers, and how to configure server-side data transmission.

What Is Microsoft Advertising Conversions API?

Conversions API is a server-side interface that allows information about user actions to be sent directly from the advertiser's infrastructure to Microsoft Advertising.

With traditional tracking, a conversion is recorded using JavaScript code in the user's browser. With server-side tracking, the event is transmitted by an online store's backend, a CRM, or another system.

For example, after an order is placed, an online store can send Microsoft Advertising confirmation of the purchase, its value, currency, and transaction ID.

CAPI supports the transmission of website events, CRM events, offline sales, and mobile application events, as well as data required for dynamic remarketing.

The main advantage is an additional independent channel for transmitting events, which helps reduce data loss caused by limitations of browser-based tracking.

Didn't Microsoft Ads Support Conversion APIs Before?

Yes, it did, but the capabilities were divided among several tools.

Universal Event Tracking (UET) is the primary tool for tracking user actions on a website. A JavaScript tag records page visits, purchases, and other events.

Offline Conversions API is a mechanism for importing conversions that occur outside the website. For example, an advertiser could submit information about a sale completed by a sales representative after a phone call.

Integrations with CRM systems and partner analytics platforms were also available.

Therefore, Microsoft did not create server-side conversion transmission from scratch.

The new aspect of CAPI is the combination of different scenarios within a single interface: from page views and adding products to a cart to order confirmation, lead qualification, or an offline purchase.

Advertisers no longer necessarily need to use a separate technical mechanism for each event source.

What Exactly Changed?

Conversions API supports two main types of events.

Page Load is a page-view event. It contains the page URL, traffic source, and other information about the visit.

Custom Event is an arbitrary user action. For example, adding a product to a cart, submitting a lead form, making a purchase, or moving a lead to the next CRM stage.

Events can contain conversion value, currency, product information, and other parameters.

To match actions with advertising clicks, Microsoft uses the msclkid identifier, as well as other permitted user identifiers.

As a result, server-side events can be used for conversion attribution and to provide signals for advertising optimization.

An additional advantage is the ability to transmit confirmed events from a business's internal systems rather than relying exclusively on actions recorded by the browser.

UET or CAPI: Which Should You Use?

Microsoft recommends using UET and CAPI together rather than replacing one tool with the other.

UET records actions directly in the browser, including information about visited pages.

CAPI supplements this data with server-side events that may contain information from an order management system or CRM.

For example, a user makes a purchase. UET records the completion of checkout in the browser, while the online store's server sends confirmation through CAPI.

Because both events relate to the same purchase, there is a risk of double counting.

Event deduplication is used to solve this problem.

Microsoft recommends sending identical eventId values and compatible eventName values for the same event in UET and CAPI, using the same UET Tag ID.

This allows the system to recognize the two signals as a single conversion.

Incorrectly configured deduplication can significantly inflate the number of purchases or leads in reporting, so it must be checked before a full launch.

How to Set Up Microsoft Conversions API

Microsoft provides several integration methods: direct API integration, partner solutions, and configuration through tag management systems.

For a custom server-side integration, the process is as follows:

1. Open the UET section in Microsoft Advertising and select an existing tag or create a new one.
2. In the tag settings, select Use Conversions API and obtain an authorization token.
3. Define the events that need to be transmitted: purchases, leads, cart actions, and CRM statuses.
4. Configure event transmission from the server to https://capi.uet.microsoft.com/v1/{tagId}/events.
5. Send the required parameters: event type, timestamp, user identifiers, value, and other data.
6. If the event is also sent through UET, configure deduplication.
7. Verify event processing, API errors, and the appearance of conversions in reporting.

For accurate attribution, Microsoft recommends storing msclkid after an advertising click and transmitting it with subsequent events.

Dynamic remarketing also requires ID Sync, which connects advertiser user identifiers with Microsoft identifiers.

What Does This Change for Advertisers?

For e-commerce, CAPI allows confirmed purchases to be sent directly from the order management system, including purchase value and cart contents.

For B2B advertisers, it provides a more unified way to transmit CRM events: qualified leads, sales inquiries, and other meaningful stages.

For companies with long sales cycles, the ability to combine user actions on a website with events recorded after the initial inquiry is especially important.

Additional signals can improve the completeness of conversion measurement and the quality of data used by automated bidding strategies.

However, implementing CAPI alone does not guarantee a reduction in CPA or an increase in ROAS.

The effect depends on how many conversions were previously lost, how correctly identifiers are configured, and whether the transmitted events correspond to actual business results.

In addition, CAPI does not eliminate requirements for user consent and personal data protection.

Limitations and Outlook

In August 2026, the new product was in beta testing.

As Microsoft continues developing it, the company is expanding its documentation and integration scenarios. However, the availability of individual features may depend on the advertising account and the selected integration method.

For agencies, the most important task is not simply to implement another tracking tool, but to ensure consistency between browser-based and server-side events.

The main result of the Microsoft Advertising Conversions API launch is a transition from fragmented data transmission methods to a unified architecture for measuring user actions.

This is particularly relevant for advertisers using Smart Bidding who want to optimize campaigns based on reliable purchase and qualified lead data, rather than browser events alone.

Sources

1. Microsoft Learn: Conversions API Integration. Microsoft Learn
2. Microsoft Learn: Offline Conversions API. Microsoft Learn
3. Microsoft Learn: Universal Event Tracking. Microsoft Learn