---
title: "Merge Tag Previews"
description: "Display merge tags replaced with test data in the Topol editor preview, and send a test email using that data."
url: https://docs.topol.io/email-editor/guide/merge-tag-previews.html
---

# Merge tag previews

**Merge Tag Previews replace merge tags with test values inside Preview mode**, so a template can be checked with realistic content before it is sent.

To use this feature, enable it in the `TOPOL_OPTIONS` configuration:

```ts
enableMergeTagPreview: true,
```

> **INFO**
>
> This works independently of [Smart Merge Tags](https://docs.topol.io/email-editor/guide/merge-tags.html#smart-merge-tags). Only `enableMergeTagPreview` is required.

Once enabled:

1.  Navigate to **Preview** mode inside the editor.

![Merge Tag Preview Button](https://docs.topol.io/merge-tags/merge-tag-preview-button.png)

2.  Click the **Merge Tags - Preview** button to toggle the Merge Tag Preview panel.

![Merge Tag Preview Panel](https://docs.topol.io/merge-tags/merge-tag-preview-panel-toggle.png)

3.  Click it to view mock values for all Merge Tags present in your email.

![Merge Tag Preview Panel](https://docs.topol.io/merge-tags/merge-tag-preview.png)

The panel lists the tags used in the current template, along with any tag referenced by a [Conditional Content](https://docs.topol.io/email-editor/guide/conditional-content.html) variant condition. A **Show unused** toggle extends the list to every defined merge tag.

To pre-fill these test values, add the `defaultValue` property to a Merge Tag's configuration and the Preview populates the input automatically. For details and an example, see [Default Merge Tag Values](https://docs.topol.io/email-editor/guide/merge-tags.html#default-merge-tag-values).