Full Answer

The two transports solve different problems. The Pixel runs in the browser, so it sees page context and fires instantly, but it's exposed to ad blockers, tracking prevention, and consent gates that silently drop events. The Events API runs server-to-server, so it survives those obstacles and can attach hashed customer data, but on its own it lacks some browser-only context. Sending both is the documented best practice because each covers the other's blind spot.

Deduplication is what makes running both safe. For every conversion, generate one event_id on your server and pass it to the Pixel call as well, so the browser and server events arrive carrying the same identifier. TikTok matches them on event_id plus event name within its dedup window and counts a single event, preferring the more complete record. Without this, a purchase fired by both paths can be counted twice, inflating conversions and misleading Smart Performance bidding.

In WooCommerce, the clean implementation is to mint the event_id when the order is created, render it into the Pixel snippet, and include it in the server payload sent to the Events API. The pattern mirrors how stores already combine the Meta Pixel with Meta's Conversions API, so if you've done that deduplication before, the TikTok version follows the same logic.