ContentBlockByKey

Parameters

Name	Type	Required	Description
`customerKey`	string	Yes	The customer key (external key) of the Content Builder asset.
`regionName`	string	No	The impression region name to associate with this content block.
`stopOnError`	boolean	No	When `true`, stops rendering if the block is not found. Defaults to `false`.
`fallbackContent`	string	No	HTML string to render if the block is not found.

Description

Platform.Function.ContentBlockByKey() renders a Content Builder block and returns the processed HTML. The returned string contains the fully rendered HTML, including any personalization variables resolved within the content block.

The content block is processed server-side, so any AMPscript or SSJS inside it also executes.

Examples

Render a content block

var headerHtml = Platform.Function.ContentBlockByKey("header-navigation");
Write(headerHtml);

With a fallback

var html = Platform.Function.ContentBlockByKey("promo-banner", null, false, "<p>No promo available.</p>");
Write(html);

Conditional content block

var sk = Platform.Request.GetQueryStringParameter("sk");
var isVIP = Platform.Function.Lookup("Subscribers", "IsVIP", "SubscriberKey", sk);

var blockKey = (isVIP === "1") ? "vip-welcome-block" : "standard-welcome-block";
Write(Platform.Function.ContentBlockByKey(blockKey));

Composing a page from blocks

Write(Platform.Function.ContentBlockByKey("page-header"));
Write('<main class="content">');
Write(Platform.Function.ContentBlockByKey("main-content-" + pageId));
Write('</main>');
Write(Platform.Function.ContentBlockByKey("page-footer"));

Notes

The customer key is set in Content Builder under the asset’s properties.
Returns an empty string (or fallbackContent) if the block is not found.
Use Platform.Function.ContentBlockByName() if you don’t have the customer key.