Destinations: Facebook CAPI, webhooks and S2S postbacks

A destination is where matched events go. XTRACKER supports three kinds, and one event can fan out to several at once.

The three kinds

Facebook CAPI (fb_capi)

Server-side Conversions API. You provide a pixel id and an access token; XTRACKER builds the CAPI payload and sends Purchase, CompleteRegistration, etc. (per your event map). For deposits, value and currency are forwarded as custom_data so Meta can optimise on revenue.

Webhook (webhook)

A generic HTTP callback to a URL you control. XTRACKER POSTs a JSON body for every matched event. Use it to push conversions into your own backend, a data warehouse, or a no-code tool. See the webhook payload reference.

S2S postback (s2s_postback)

Affiliate-network style. You give a url_template with macros like {uid} and {value}; XTRACKER fills them in and fires a GET (or POST). See the postback macro reference.

Adding one is the same flow for every kind — pick the kind, fill its fields, save:

Durable delivery

Events are never fire-and-forget. The flow is:

1. An event lands in event_inbox (durable, deduped).
2. It fans out to one event_outbox row per destination.
3. A worker dispatches each row and records the outcome.

If a destination is down or returns a transient error (408, 429, 5xx), the row is retried with exponential backoff — the first retry after ~30s, capped, up to a maximum number of attempts before it's marked failed_permanently. A permanent error (a bad URL, a 4xx that isn't retryable) fails fast without burning retries.

This means a momentary outage at Meta or your endpoint never loses a conversion.

Proxies

Each destination can route its outbound traffic through a per-destination proxy — useful for Meta pixels that must originate from a specific region.

Statuses on the dashboard

The delivery health widget shows, per destination: sent, pending, failed, failed_permanently. Watch failed_permanently — that's where a misconfigured URL or a rejected token surfaces.

Next

• Event maps — map canonicals to each destination's names.
• Webhook payload reference — the exact JSON body.
• S2S postback macros — the full macro table.