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Real-Time HTML Editor

Type HTML and CSS in the editor pane and see the live rendered result immediately — no save button, no refresh, just instant feedback.

Last updated: May 26, 2026

Client-Side Processing
Input Data Stays on Device
Instant Local Execution

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What is Real-Time HTML Editor?

A real-time HTML editor lets you write HTML (with inline CSS and JavaScript) and see the rendered result update as you type. It is the fastest way to prototype a layout, test a CSS rule, debug a markup problem, or experiment with a web concept without setting up a local development environment.

The preview runs inside a sandboxed iframe — a separate browsing context that cannot access the parent page's JavaScript or cookies. This means you can safely run arbitrary HTML, CSS, and JavaScript in the preview without affecting the tool itself. The sandbox allows scripts (`allow-scripts`), same-origin access for resources, and form submissions — enough to render realistic pages while isolating execution.

How to Use Real-Time HTML Editor

1

Edit the HTML in the left pane — the preview updates on every keystroke.

2

Use the Split / Editor / Preview buttons to choose your preferred layout.

3

Click Reset to restore the starter template.

4

Click Download to save the page as index.html, or Copy to copy the code.

Common Use Cases

  • Quickly prototyping a new layout idea without opening a code editor.
  • Teaching HTML and CSS with an instant feedback loop.
  • Testing how a small HTML snippet renders before adding it to a project.
  • Debugging CSS by tweaking values and seeing the result immediately.
  • Generating a standalone HTML page for a quick demo or email mockup.

Example Input and Output

A simple card component with CSS renders instantly in the preview pane.

HTML + CSS
<style>.card{border:1px solid #ddd;border-radius:8px;padding:1rem;}</style>
<div class="card"><h2>Hello</h2><p>Live preview!</p></div>
Rendered preview
Rendered card with border and padding visible in the preview iframe.

Privacy

Your HTML is never sent to a server. Everything runs locally in your browser.

Sandbox security

The preview iframe uses sandbox="allow-scripts allow-same-origin allow-forms". Popups, top-level navigation, and storage access are blocked, which prevents the preview from escaping the iframe.

Frequently Asked Questions

Can I use JavaScript in the preview?
Yes. JavaScript runs inside the sandboxed iframe. It cannot access the parent page, cookies, or localStorage of the tool itself.
Can I load external resources like fonts or images?
Yes — the iframe has network access and can load resources from external URLs. Just make sure the URLs use https.
Does this save my work?
No. The editor is stateless — if you close or refresh the page, your work is lost. Download or copy the code before leaving.
Is there a size limit?
No hard limit, but very large HTML files may cause the preview to update slowly because the iframe re-renders on every keystroke.

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Part of a Collection

Collection
Free Online HTML Tools
Clean, convert, and generate HTML in your browser