AdFixus Powers Conversion APIs for the Open Web & Anonymous Audiences

Introduction

In today’s privacy-first digital era, traditional browser-based tracking is crumbling under iOS privacy updates, third party cookie deprecation, and increasing user consent controls. Conversion APIs (CAPI), also known as server side conversion tracking, have emerged as trusted alternatives. AdFixus uniquely combines CAPI capabilities with its patented anonymous identity solution to deliver transparent, privacy protected performance across the open web.

What Is CAPI and Why It Matters

As defined in sources like Funnel and Licera inc, Conversion APIs allow businesses to send user interaction events, from purchases to page views, directly from their servers to ad platforms (e.g. Meta) without relying on browser tracking or cookies. 
This server-to-server model improves data accuracy and resilience, it bypasses ad blockers, mitigates signal loss from browser restrictions and improves ad attribution and optimisation using first party data. And it is this performance and reportability that has really seen it take off. The ROI is being reported on against the spend, performance and outcomes to the business. 

Nearly all the large ad platforms now have a CAPI or related product. Meta was the first to release one in 2020, followed by Google, TikTok, Snap, Pinterest, LinkedIn, Spotify, Yahoo DSP and others.

The big issue is that this only works for known or login users. Why? The connection is based on PII linkages. This misses a large portion of a sites traffic (anonymous) to help guide people in the decision set to a business outcome. 

This is very important for both parts of the partnership. If the publisher and / or the advertiser doesn’t have a large, authenticated pool of users to match on then the viability is reduced. Having the same ID infrastructure both sides of the partnership enables full audience addressability and connectivity.  
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Why AdFixus Enhances CAPI Implementations

Privacy-first Identity ‍
AdFixus uses its patented Anonymous Federated ID (AFxID), a completely anonymized, consent-driven identifier that requires no PII, is double-encrypted, browser-stored, and revocable anytime. 

Extending Reach Across the Open Web
AdFixus is unique in that it enables advertisers to understand both authenticated and anonymous users on all browsers (including Safari and iOS) and connect that data to publishers without third-party cookies. And all in real-time. 

A real-world example: partnering with Carsales and the AdFixus powered CAPI product, clients have seen a 300% increase in conversion events when compared against standard segmentation.

Full-Funnel CAPI Powered by Machine Learning
AdFixus’ platform combines CAPI-driven server events with anonymous identity data to deliver full-funnel insights, from first visit through conversion, within a privacy compliant framework. Publisher side AI-powered attribution and cohort modelling allow optimized targeting, lookalike audiences, and more accurate performance measurement. 

Benefits of AdFixus Powered CAPI

• Complete Attribution: Captures conversions lost to ad blockers or browser restrictions; deduplicated between browser and server events

• Open-Web Capability: Stable identity within the browser extends CAPI to anonymous visitors across publishers

• Privacy-Compliant: Identity requires no PII, can be revoked at any time, and is generated only with consent

• Performance & Efficiency: AI-powered cohort modelling and lookalike targeting improve ROAS and conversion visibility

How It Works: Step-by-Step

1. User visits publisher site and consents → AFxID generated and stored.

2. User clicks on the ad and lands on client website

1. In-session user actions captured → purchase, form fill, pageview, CRM events.

2. Server sends event with client AFxID and context to publisher via CAPI and converts to publisher AFxID.

3. Publisher picks up events in real-time and optimizes campaign – remarketing, sequential messaging, suppression.

4. Publisher can extend capabilities for lookalikes and campaign expansion.  

The AdFixus Difference

• Anonymous-first identity, unmatched reach into formerly opaque anonymous audiences.

• Server-side CAPI tracking that is resilient, reliable, and compliant.

• Machine learning-driven attribution and targeting powered by real first-party behaviour data.

• Real-world performance proven through clients like Carsales, delivering 300% reach uplift and triple conversion rates.

Conclusion

AdFixus isn’t just deploying CAPI, it’s redefining what CAPI can achieve in a privacy-conscious world. By pairing AdFixus’ secure Anonymous Federated ID (AFxID) with advanced CAPI tracking, advertisers can finally marry the best of walled garden reliability with open web extensibility. The result? Better data, better measurement, and better performance, without compromising user trust.

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Interested in deploying AdFixus-powered CAPI for your open web or anonymous audiences? I’d be happy to help you put this into action – sales@adfixus.com

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