Meta Conversions API for embedded forms

When Meta Conversions API (CAPI) delivery is enabled, Siv sends a server-side Lead event for each accepted Siv web-form submission. Pair it with your website's browser Pixel event. Meta can then deduplicate the browser and server events.

Configure server-side delivery

In Siv, open Settings > Facebook for the property.
Under Meta Conversions API, enter the Dataset (Pixel) ID that your website's browser Pixel uses. Enter a dedicated CAPI access token.
Leave Send Lead events for Siv web-form submissions selected.
To test the connection, enter a current Meta test event code and select Save and validate. Siv uses the code for that request only and does not save it.

This integration sends conversions for accepted Siv web-form submissions only. It does not send CAPI conversions for Facebook Lead Ads imported into Siv.

Deduplicate the browser event

Use the callback's exact eventId as Meta Pixel's eventID:

The browser event and Siv's server event must share all three values:

Event name: Lead
Event ID: the callback's exact eventId
Dataset (Pixel) ID: the same dataset configured in Siv and on the website

Meta cannot deduplicate events sent to different datasets. Siv does not load or call the browser Pixel.

Conversion value

Siv reports the requester's estimated budget as the event's conversion value, so Meta can optimize toward the leads worth the most rather than toward lead volume alone:

Siv omits the value, and sends the Lead without one, when any of the following is true:

The requester left the budget blank or entered zero.
The amount is implausible for a single event. Siv treats anything above 1,000,000 as a data-entry error rather than a value.

The budget is what the requester typed on the form. It is neither a quote nor a contract value, and it usually describes their whole event spend rather than the portion your property would capture. Treat it as a relative ranking signal, not revenue.

All values are reported in US dollars. Siv does not yet record a per-property currency.

Keep the value through deduplication

When Meta deduplicates a browser event against a server event, it keeps whichever it received first. A browser Lead sent without a value can therefore suppress the value on Siv's server event.

To keep the value, either send the same custom_data on your browser event, or send no browser event and let Siv's server event stand alone.

Run browser advertising calls only after your consent platform says they are allowed. Store the CAPI token only in Siv settings; never place it in the embed snippet or submission callback.

Troubleshooting duplicate leads

Compare the browser and server events in Meta Events Manager. Confirm both say Lead, carry the same event ID, and target the same Dataset (Pixel) ID.

If server delivery fails, check its latest status under Settings > Facebook > Meta Conversions API, then validate the saved token with a fresh test event code.

Confirming the conversion value

A successful delivery does not prove Meta recorded the conversion value. Meta answers a payload whose custom_data it discarded exactly as it answers a good one, so neither Siv's delivery status nor Meta's API response distinguishes the two.