> For the complete documentation index, see [llms.txt](https://help.clickatell.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.clickatell.com/developers-documentation/applications/chat-flow-external-link-handler-api.md).

# Chat Flow - External Link Handler API

## **Why use this API?**

The [External Link Handler API ](broken://pages/9PTbrGfGmnqM9rRXP8U3)lets you direct an end-user to an external web page from within a Chat Flow conversation and return to the Chat Flow conversation with optional additional data gathered from the external web page. 

## **When to use this API**

This API is used with the [External Link node](https://guides.clickatell.com/flow/user-facing-nodes/display-nodes/menu-nodes-external-link) in [Chat Flow](https://guides.clickatell.com/flow) to call an external web URL and enable the URL to return a single variable result to your workflow.

Typical use cases include:

* Directing end-users to a website to read terms and conditions or to complete a survey.
* Creating an out-of-band authentication module using a web URL.
* Handing over end-user communication to another channel triggered via a web URL (e.g., a web-based chat or VOIP call into an IVR).

##  **Getting started with the External Link Handler API**

1. Build a workflow in [Chat Flow ](https://guides.clickatell.com/flow)containing an [*External Link* node](https://guides.clickatell.com/flow/user-facing-nodes/display-nodes/menu-nodes-external-link).
2. Add the [*/callback* endpoint](broken://pages/9PTbrGfGmnqM9rRXP8U3) into the website back-end script. This endpoint handles the return call from an external service, takes in a response and any additional information, and then continues the conversation with the end-user. 
   * Ensure that what your system passes back as the result matches what you have constructed in Chat Flow, especially the results specified in the "*Logic"* section of the External Link node.

{% hint style="warning" %}
JavaScript is **not** supported for this callback endpoint.
{% endhint %}

<img src="https://content.gitbook.com/content/paUgSvJj6dcuDMhPgWb4/blobs/9IfigRjXI8FAFX15SKX2/image.png" alt="" height="524" width="531">

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