The Pixel runs in the visitor's browser. Browsers and ad blockers can stop it. Conversions API sends the same event from your server, so Meta still hears about the sale.
Why you want both
Send events from the Pixel and from Conversions API, with the same event ID. Meta removes duplicates and keeps the most complete data.
Easiest setup
- On Shopify, WooCommerce or WordPress, use the platform's Meta integration and switch on Conversions API.
- On a custom site, ask your developer to send Purchase and Lead events from the server.
- Check Event Match Quality in Events Manager. Sending hashed email and phone helps.
Decifile's Tracking health page checks this for you every day.