Advertisers often ask whether they should use the pixel or CAPI. The honest answer for most is: both, working together. Understanding the difference is the key to a healthy setup.
The pixel: browser-side tracking
A pixel is a snippet of code that runs in the user's browser and reports actions back to the platform. It's easy to deploy but increasingly fragile, blocked by ad blockers, limited by iOS and browser privacy changes, and dependent on cookies that don't always survive.
CAPI: server-side tracking
CAPI sends the same conversion events from your server directly to the platform. Because it doesn't depend on the browser, it captures conversions the pixel misses, making it far more resilient to privacy restrictions and signal loss.
Why you need both
The pixel captures rich browser context; CAPI captures the conversions the browser drops. Together they give platforms the most complete picture. The critical piece is deduplication: shared event IDs so the same conversion sent by both isn't counted twice.
- Pixel: rich context, fragile delivery
- CAPI: resilient delivery, needs good parameters
- Together + deduplication: complete, accurate signal
Related reading: our services and the Measurement Health Audit.
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