> For the complete documentation index, see [llms.txt](https://docs.tryterra.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tryterra.co/help-center/help-topics/data-api-sdk/webhooks-dedup-and-sync-reliability/track-webhook-request-completion.md).

# How do I know when a data request's last event arrived?

The API response to a to\_webhook=true request returns a reference field in its JSON body, and the webhook deliveries for that request carry the same value in their terra-reference header.

**The API response to a `to_webhook=true` request returns a `reference` field in its JSON body, not a `terra-reference` response header.** The webhook deliveries for that request carry the same value in their `terra-reference` header, so store the body's `reference` and match deliveries against it to track completion.

Data for a request usually arrives in a **single delivery**. The exception is **Garmin**, which sends data asynchronously in batches that Terra forwards as they arrive.