How do I open an HTML file online?

Open the .html file in a plain-text editor, copy the source code, and paste it into the editor pane here. The preview renders the page straight away - nothing is uploaded and nothing needs installing.

What should I open a .html file with?

Double-clicking it opens the rendered page in your browser; opening it with Notepad, TextEdit or a code editor shows the source code. This viewer gives you both at once - code on the left, rendered result on the right.

Do .htm and .mhtml files work?

A .htm file is the same thing as .html, so its source code pastes in fine. .mhtml is a packed archive of a page plus its assets, so its raw content will not render here - re-save it as plain HTML first.

Can I open an HTML file on iPhone or Android?

Yes. This page works in mobile Safari and Chrome; on phones the editor and the preview stack vertically. To reach a file stored on the device, open it from Files or your file manager with a text editor and copy the code across.

Can I convert HTML to PDF here?

Not directly - this tool renders and edits HTML only. Once the preview looks right, copy the HTML into a local .html file, open it in your browser and use Print, then choose Save as PDF as the destination.

Do external CSS, JavaScript and images load in the preview?

Absolute https URLs load normally, so CDN stylesheets, scripts and images all work. Relative paths like ./style.css cannot resolve because the preview has no directory of its own. The frame is sandboxed with scripts allowed but no same-origin access, so cookies, storage and alert dialogs stay blocked.

Can I save or download the result?

There is no download button. Use Copy to take the markup out, paste it into a .html file on your machine and save it there - your code never leaves the browser in the first place.

HTML Viewer

Paste HTML and see it rendered instantly in a live preview beside the editor. No upload, no install - everything runs locally in your browser, free.

To open an HTML file online, copy the source code out of your .html file and paste it into the editor on the left - the panel on the right renders the page instantly. You get a live rendered preview, an editable syntax-highlighted HTML editor, one-click copy and a fullscreen mode. Everything runs inside your browser in a sandboxed iframe, so nothing is uploaded anywhere.

HTML Viewer

1484

Editor

Code

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <style>
        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            display: flex;
            justify-content: center;
            align-items: center;
            height: 100vh;
            margin: 0;
        }
        .card {
            background: rgba(255, 255, 255, 0.2);
            backdrop-filter: blur(10px);
            padding: 2rem;
            border-radius: 1rem;
            box-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.37);
            border: 1px solid rgba(255, 255, 255, 0.18);
            text-align: center;
            max-width: 400px;
        }
        h1 { margin-top: 0; }
        button {
            background: white;
            color: #764ba2;
            border: none;
            padding: 0.8rem 1.5rem;
            border-radius: 2rem;
            font-weight: bold;
            cursor: pointer;
            transition: transform 0.2s;
        }
        button:hover {
            transform: scale(1.05);
        }
    </style>
</head>
<body>
    <div class="card">
        <h1>Hello World!</h1>
        <p>This is a live preview of your HTML code.</p>
        <button onclick="alert('It works!')">Click Me</button>
    </div>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <style>
        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            display: flex;
            justify-content: center;
            align-items: center;
            height: 100vh;
            margin: 0;
        }
        .card {
            background: rgba(255, 255, 255, 0.2);
            backdrop-filter: blur(10px);
            padding: 2rem;
            border-radius: 1rem;
            box-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.37);
            border: 1px solid rgba(255, 255, 255, 0.18);
            text-align: center;
            max-width: 400px;
        }
        h1 { margin-top: 0; }
        button {
            background: white;
            color: #764ba2;
            border: none;
            padding: 0.8rem 1.5rem;
            border-radius: 2rem;
            font-weight: bold;
            cursor: pointer;
            transition: transform 0.2s;
        }
        button:hover {
            transform: scale(1.05);
        }
    </style>
</head>
<body>
    <div class="card">
        <h1>Hello World!</h1>
        <p>This is a live preview of your HTML code.</p>
        <button onclick="alert('It works!')">Click Me</button>
    </div>
</body>
</html>

Preview

Live Preview

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How to use the HTML viewer

1
Copy your HTML source
Open the .html file with a plain-text editor - Notepad on Windows, TextEdit on macOS, or any code editor - and copy everything.
2
Paste it into the editor
Drop the code into the left pane. You can also press Sample to load a ready-made demo page and start from there.
3
Read the live preview
The right pane renders the markup roughly half a second after you stop typing, exactly as a browser would.
4
Edit, copy, go fullscreen
Adjust the markup and watch the result change, use Copy to take the HTML back to your project, or Fullscreen for a bigger workspace.

References

MDN - HTML
Reference and tutorials for every HTML element and attribute.
WHATWG - HTML Standard
The living specification that defines HTML syntax and how browsers render it.
MDN - The iframe element and its sandbox attribute
Explains the sandbox restrictions this tool applies to the preview frame.

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Frequently Asked Questions

How do I open an HTML file online?: Open the .html file in a plain-text editor, copy the source code, and paste it into the editor pane here. The preview renders the page straight away - nothing is uploaded and nothing needs installing.
What should I open a .html file with?: Double-clicking it opens the rendered page in your browser; opening it with Notepad, TextEdit or a code editor shows the source code. This viewer gives you both at once - code on the left, rendered result on the right.
Do .htm and .mhtml files work?: A .htm file is the same thing as .html, so its source code pastes in fine. .mhtml is a packed archive of a page plus its assets, so its raw content will not render here - re-save it as plain HTML first.
Can I open an HTML file on iPhone or Android?: Yes. This page works in mobile Safari and Chrome; on phones the editor and the preview stack vertically. To reach a file stored on the device, open it from Files or your file manager with a text editor and copy the code across.
Can I convert HTML to PDF here?: Not directly - this tool renders and edits HTML only. Once the preview looks right, copy the HTML into a local .html file, open it in your browser and use Print, then choose Save as PDF as the destination.
Do external CSS, JavaScript and images load in the preview?: Absolute https URLs load normally, so CDN stylesheets, scripts and images all work. Relative paths like ./style.css cannot resolve because the preview has no directory of its own. The frame is sandboxed with scripts allowed but no same-origin access, so cookies, storage and alert dialogs stay blocked.
Can I save or download the result?: There is no download button. Use Copy to take the markup out, paste it into a .html file on your machine and save it there - your code never leaves the browser in the first place.