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Hazuu Tools

HTML Viewer

Preview your HTML in a live sandbox and inspect it with color-coded syntax highlighting.

HTML Input
Preview
visibilityPreview will appear here...
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About HTML Viewer

HTML Viewer is a free online tool that lets you paste any HTML code and instantly see both a live rendered preview and a syntax-highlighted source view side by side. It closes the gap between raw markup and what actually appears in a browser window, so you can verify layout, check styling, and audit structure without spinning up a local server or opening a text editor.

You would reach for this tool when someone sends you an HTML snippet and you want to know what it looks like rendered, when you are debugging a template from a CMS or email builder, when you need to inspect the color-coded structure of a file you did not write, or when you want a quick sanity check on hand-coded markup before committing it. The two-pane interface lets you edit in the left textarea and click Render to update the preview or source view on the right, with a warning bar that flags potentially unclosed tags.

All rendering and syntax highlighting runs entirely in your browser — the tool never uploads your code to any server. The preview uses a sandboxed iframe with the allow-scripts permission, which is enough to render CSS and JavaScript accurately while blocking access to your parent page, cookies, and localStorage. There is no account, no rate limit, and no cost.

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Key Features

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Live sandboxed preview

HTML renders inside an iframe with sandbox="allow-scripts", giving you an accurate browser-like preview while blocking access to your session data or parent page.

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Syntax-highlighted source view

Switch to Source mode to see your markup color-coded: tags in blue, attribute names in amber, attribute values in green, and comments in gray, making structure easy to scan.

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Unclosed-tag warning

The tool runs a lightweight tag-balance check before rendering and shows an amber warning bar listing any potentially unclosed tags, helping you catch structural errors at a glance.

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File upload support

Load an .html, .htm, or .txt file directly from your computer using the upload button — no copy-paste required for larger documents.

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100% client-side

Nothing leaves your machine. Rendering, syntax highlighting, and tag checking all happen in the browser, so proprietary templates and work-in-progress markup stay private.

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Sample HTML for instant testing

Hit the Sample button to load a working example featuring a styled card component. Useful for exploring the tool or testing color-scheme changes without writing markup from scratch.

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How to Use

01

Enter Your HTML

Paste your HTML code into the input editor on the left, or upload an .html file from your computer.

02

Click Render

Press the "Render" button to generate a live preview of your HTML in a sandboxed iframe.

03

Switch Views

Toggle between "Preview" to see the rendered page and "Source" to view the code with syntax highlighting.

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Example

Paste a self-contained HTML snippet. Click Render to see it drawn in the Preview pane on the right, or switch to Source to inspect the color-coded markup.

HTML input (left pane)
<!DOCTYPE html>
<html lang="en">
<head>
  <style>
    body { font-family: system-ui, sans-serif; padding: 24px; }
    .alert { background: #fef9c3; border: 1px solid #fbbf24;
             border-radius: 8px; padding: 16px; }
    .alert strong { color: #92400e; }
  </style>
</head>
<body>
  <div class="alert">
    <strong>Note:</strong> Deployment scheduled for Friday at 18:00 UTC.
  </div>
</body>
</html>
Preview output (right pane)
Rendered in the Preview pane:

  [Yellow alert box]
  Note: Deployment scheduled for Friday at 18:00 UTC.

Switch to Source view to see tags highlighted:
  <div> in blue, class= in amber, "alert" value in green.
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Common Use Cases

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    Checking HTML email templates

    Email clients strip or override CSS in unpredictable ways. Paste the raw source of a marketing or transactional email to verify the rendered layout and catch broken table structures before you send.

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    Reviewing CMS or page-builder output

    WordPress, Webflow, and similar tools generate HTML you did not write. Drop the exported markup into the viewer to audit what is actually there — hidden wrappers, inline styles, and all — without loading the full CMS.

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    Debugging HTML snippets from colleagues or Stack Overflow

    When someone pastes HTML into a chat or issue tracker, rendering it here tells you in seconds whether the snippet is complete and structurally valid before you start integrating it.

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    Inspecting third-party widget or embed code

    Embeds from analytics, chat widgets, and ad networks come with opaque HTML. Use the syntax-highlighted Source view to understand the tag structure and attribute values without a browser DevTools session.

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    Teaching and learning HTML structure

    The split preview-plus-source view makes the tool useful in coding education: write or paste a snippet, render it, then flip to Source mode to trace exactly which tags produced each part of the visual output.

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Frequently Asked Questions

What is an HTML Viewer? expand_more
An HTML Viewer is a tool that lets you paste or upload HTML code and instantly see how it renders in a browser. It combines a live preview with a syntax-highlighted source view, making it easy to inspect, debug, and understand HTML markup.
Is it safe to preview untrusted HTML? expand_more
Yes. The preview runs inside a sandboxed iframe with restricted permissions. Scripts are allowed within the sandbox so CSS and JS render correctly, but the sandbox prevents access to your parent page, cookies, and other browser data.
Does my HTML get sent to a server? expand_more
No. All rendering and syntax highlighting happens entirely in your browser. Your code never leaves your machine, so it is safe to use with proprietary or sensitive markup.
What does the syntax highlighting show? expand_more
The source view color-codes your HTML for readability: tags appear in blue, attribute names in amber, attribute values in green, and comments in gray. This makes it easy to scan and understand the structure of your code at a glance.
How is HTML Viewer different from an HTML editor like a realtime HTML editor? expand_more
HTML Viewer is read-focused: you paste existing markup to inspect or debug it, and the syntax highlighting makes tag structure visible at a glance. A realtime editor is write-focused — it is designed for composing new HTML with live feedback as you type. Use the Viewer when you have markup to audit, and the realtime editor when you are authoring from scratch.
Can it render HTML that includes CSS and JavaScript? expand_more
Yes. The sandboxed iframe allows scripts and styles to run, so pages with inline or embedded CSS and JavaScript will render accurately, including animations and dynamic content.
What file types can I upload? expand_more
The upload button accepts .html, .htm, and .txt files. The file is read entirely in your browser using the FileReader API; nothing is uploaded to a server.
Does the tool warn me about broken HTML? expand_more
Yes. Before rendering, the tool checks for unclosed tags. If it finds any, an amber warning bar lists the tag names. The preview still renders — browsers are tolerant of malformed HTML — but the warning helps you spot structural mistakes early.
Is there a size limit on the HTML I can render? expand_more
There is no fixed limit enforced by the tool. Because everything runs locally in your browser, the practical ceiling is your device memory. Very large pages with many DOM nodes may be slow to render, but typical snippets and full HTML documents load instantly.