Your Facebook Pixel Is Lying to You - Here's How CAPI Fixes It

• AdBlock - script never loaded at all.
• iPhone with "limit ad tracking" - click ID gets stripped before the user even hits your landing.
• Safari - cookie dies after 7 days instead of 90.

Worth knowing: just turning CAPI on isn't enough. If your server isn't passing user identifiers (email, phone, fbp, fbc, etc.), your match quality can end up just as bad as a plain pixel.

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• Works only on the event_name + event_id pair - not by user, not by email
• Window is 48 hours - server event comes in later than that, the conversion doubles

Fast Tech Support said:

You're running ads, leads are coming in, CRM shows one number, Meta shows another. Sound familiar? Let's break down why.
Most likely it's the pixel - it lives in the user's browser, and browsers today are killing your data from every angle:

• AdBlock - script never loaded at all.
• iPhone with "limit ad tracking" - click ID gets stripped before the user even hits your landing.
• Safari - cookie dies after 7 days instead of 90.

And none of this makes any noise. You won't know it's happening. Events Manager won't save you either - it only shows what actually came through. How much got lost? It'll never tell you.

This is where CAPI comes in. The event fires from your server directly to Meta - the user's browser is completely out of the equation.
But honestly, that's not even the best part. CAPI lets you send events that happen long after the user left your page: deposit confirmed in CRM three hours later, lead status updated.Pixel never sees any of that.


EMQ - Event Match Quality
Meta rates your events on a scale of 1 to 10 - how well they match against real Facebook accounts. The higher the score, the better the algorithm understands who to target, and the cheaper your conversions get.

Deduplication
Running pixel and CAPI together means the same event fires twice. You solve it with event_id - generate a unique ID per conversion and send the same one from both sides. Meta spots the match and counts it once.
A few things to keep in mind:

• Works only on the event_name + event_id pair - not by user, not by email
• Window is 48 hours - server event comes in later than that, the conversion doubles

Quick check: open Events Manager and look for duplicate flags next to your Purchase or Lead events

Anyone already running pixel + CAPI - seen a difference in CPL or cost per conversion?

- FastTech

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