**Source URL:** https://general.veevavault.dev/medical/vault-api/references/reference-id.md

# Reference ID



For additional tracking purposes, every Vault API call will accept an optional string-based reference ID.
You can provide this data inside the `X-VaultAPI-ReferenceID` HTTP request header.

Vault API will record the reference ID value for each API call. This ID appears in the **API Usage Logs**, which you can download through the [UI](https://platform.veevavault.help/en/gr/14341) and [API](/vault-api/api-reference/26.1/logs/download-daily-api-usage). If an API request does not include a reference ID, the value will appear blank in the API Usage Log. The API Usage Log is only available in v18.1+, but reference ID can be included in requests for v23.3+ of Vault API.



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