# Live Preview — Template Engine — PostFrame — EternalEngine

See your template rendered with real test data side-by-side as you edit. Every change is visible instantly.

[Back to Templates](https://eternalengineos.io/features/postframe/templates/)

Template Engine

# Live Preview

The editor shows a rendered preview in an iframe that refreshes a moment after you stop typing — in visual, HTML, split or plain-text mode — with the preheader shown as it will read in the inbox list.

[Start free](https://app.eternalengineos.io/signup?plan=free&interval=annual)[Template engine overview](https://eternalengineos.io/features/postframe/templates/)

## Edit and Preview Together

Split-pane editor

Template code on the left, rendered preview on the right — updated in real-time

Save, then send a test

Once the template is saved, Send Test delivers it to your own inbox through the real pipeline

Four editor modes

Visual block editor, raw HTML, split view and plain text — the preview follows whichever you are in

Preheader preview

The preheader is edited beside the subject with a 200-character counter, since inboxes show it after the subject

Preview Features

Real-time rendering

Preview updates as you type — no refresh needed

Block editor

Headings, text, buttons, images and dividers as blocks; switch to HTML at any time

Send Test

Send the saved template to your own inbox from the same screen

Variable highlighting

Handlebars variables highlighted in source view

## Keep exploring PostFrame

[### Test sends A real send with a [TEST] subject prefix. Open Test sends →](https://eternalengineos.io/features/postframe/templates/test-sends/)[### Handlebars syntax Placeholders, conditionals, loops and helpers. Open Handlebars syntax →](https://eternalengineos.io/features/postframe/templates/handlebars-syntax/)[### Responsive design Single-column tables and inline styles. Open Responsive design →](https://eternalengineos.io/features/postframe/templates/responsive-design/)

Questions

## Common questions, straight answers.

How quickly does the preview update?

A short moment after you stop typing. The editor debounces changes, rebuilds the HTML, and reloads the preview frame, so it never lags behind fast typing.

Which editor modes are there?

Visual (block editor), HTML, split (code beside preview) and plain text. Switching from visual to HTML keeps the generated markup so you can hand-edit it.

Does the preview show my variables filled in?

The editor preview shows the template markup; to see it rendered with real values, use the preview endpoint with sample variables or send yourself a test.

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