Send server-side conversion events to Meta's Conversions API with Pixel deduplication
domain: advertising · 6 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Generate one shared event_id per real user action and pass it to both the client-side Pixel fbq call and the server-side Conversions API payload for that same action
POST the server event to the dataset/Pixel's /events endpoint with event_name, event_time, action_source, SHA-256-hashed user_data, and the matching event_id
Include as many available user_data identifiers as possible (hashed email, phone, fbp/fbc cookies, client IP, user agent) to improve Event Match Quality — a separate concern from deduplication
Confirm dedup is working via Events Manager's deduplication diagnostics, since Meta only merges events when event_name and event_id are byte-identical between Pixel and CAPI within the matching window
Batch multiple server events per request instead of issuing one HTTP call per event
Validate payloads against the Test Events tool using test_event_code before sending production traffic
Known gotchas
Any mismatch in event_id casing, whitespace, or event_name between Pixel and CAPI silently breaks deduplication and inflates reported conversions
Deduplication does not use user_data identifiers at all — consistent hashed emails without a matching event_id will not prevent double counting
action_source must accurately reflect where the event happened (website vs app vs system_generated) or attribution can be misassigned
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