---
title: Pass fields and UTM attribution through the SDK
date: 2026-08-18
slug: pass-fields-and-utm-attribution-through-the-sdk
author: Uku Tammet
---

Your website can now pass known customer data and UTM attribution to Handhold when opening an agent through the SDK. The values are stored with the new session and can flow into your CRM through automations.

- **Pass known field values.** Send values for configured Handhold fields by field ID, so the agent can use data your site already has instead of asking for it again.
- **Preserve campaign attribution.** Pass UTM source, medium, campaign, term and content directly when opening the agent.
- **Map everything into HubSpot.** Custom fields and all five UTM values are available as automation mapping sources, so contacts keep the right customer and attribution data.

See the [API reference](/docs/api) for the API reference and a copyable example.