---
title: Recognise returning visitors through the SDK
date: 2026-08-19
slug: recognise-returning-visitors-through-the-sdk
author: Sander Rõuk
---

Pass your own user identifier when opening an agent and Handhold recognises the visitor when they come back, on any device or browser.

- **Pick up where they left off.** Returning visitors get their start screen prefilled and the agent remembers previous conversations, so nobody restarts from zero.
- **Works across devices.** Recognition no longer depends on the visitor's browser storage. The same identifier means the same visitor, whether they return on a laptop, a phone or a cleared browser.
- **One line of integration.** Add `externalVisitorId` to your `openDemo` call with an identifier your product already knows.

**Security note:** the identifier is a credential. Anyone who presents it is treated as that visitor, sees their previously shared answers and can continue their conversations. Use an opaque, unguessable value, never an email address or a sequential number, and only pass it on pages where the visitor is signed in. The [API reference](/docs/api) has the details.