Glossary entry

What is the Conversion API (CAPI)?

The Conversion API sends conversion events from your server directly to ad platforms, bypassing the user's browser. It's the iOS-14-resilient backbone of modern attribution, recovers 20 to 40% of conversions hidden by ad blockers and tracking opt-outs, and is now table stakes on Meta, TikTok, and Google.

Why server-side beats browser-side

Browser pixels are blocked by ad blockers, Safari ITP, iOS opt-outs, and any GDPR consent decline. Server-side events are sent from your backend after the conversion is verified. Nothing in the user's browser can stop them.

How implementation works

Either via a tag manager (Google Tag Manager Server-Side, Stape, Tealium) or direct server code. You hash personal identifiers (email, phone) before transmission to comply with privacy rules. Then dedupe with the browser pixel using event_id.

Common implementation mistakes

Not deduplicating (causes double-counted conversions), missing match keys (degrades signal quality), firing CAPI before payment is verified (counts failed orders), and forgetting to refresh tokens (stops the feed silently).

How Unled Network helps

Every Managed Campaign client gets a CAPI implementation review and rebuild as part of onboarding. We deduplicate events and verify match quality monthly.

Related Unled Network services

• Managed Campaigns
• Lead Generation

Frequently asked

Related terms

• Pixel
• First-Party Data
• Attribution Window
• Lookalike Audience