HTML Preview

HTML Preview is a free online tool that renders your HTML as a live web page while you type. Paste or write markup in the editor and the result appears instantly in a preview pane beside it — no files to save, no local server to start and nothing to install.

Because it runs entirely in your browser, it is the fastest way to check a snippet, debug a layout or share a quick demo. Your code is never uploaded to a server, so it is safe to use even for work-in-progress or private markup.

A desktop workflow usually means creating a file, opening it in a browser and refreshing on every change. An online preview removes all of that friction:

• Instant feedback — the preview updates as you type, so you see changes immediately.
• Nothing to install — it works in any modern browser on any operating system.
• Private by default — your markup stays on your machine; nothing is uploaded.
• Shareable snippets — copy your cleaned-up HTML to paste into docs, an email or a ticket.
• Great for learning — experiment with tags, CSS and JavaScript and watch the effect in real time.

You can preview a full page — structure, styling and behaviour — all at once:

1. Type or paste your HTML into the editor on the left.
2. Add styling inside a <style> tag, or inline with the style attribute.
3. Add behaviour inside a <script> tag — the sandbox runs JavaScript, so interactive demos work.
4. Watch the preview pane render everything live as you edit.

There is no separate "run" step — the output refreshes automatically. Use Beautify to tidy messy markup, Copy to grab the HTML, or open the preview full screen to inspect a layout at real size.

HTML Preview is handy whenever you need to see markup rendered without spinning up a project:

• Testing a snippet from documentation, Stack Overflow or an AI assistant before pasting it into your codebase.
• Debugging a broken layout or a stray tag in isolation.
• Previewing an HTML email or newsletter template.
• Teaching or learning HTML, CSS and JavaScript with instant visual feedback.
• Prototyping a small component or landing section.
• Checking how a block of AI-generated HTML actually looks.

Your HTML renders inside a sandboxed iframe — an isolated frame that cannot read this page, your cookies or your browser storage. JavaScript in your snippet runs so interactive demos work, but it is confined to that frame and cannot affect the rest of the site.

Just as important, everything happens locally in your browser. Your markup is never sent to a server, logged or stored, which is why it is safe to preview private or unfinished code. When you close the tab, it is gone.

A few habits make previewing smoother:

• Keep CSS in a single <style> block near the top so it is easy to tweak.
• Put <script> at the end of the body so it runs after the markup exists.
• Use Beautify before copying, so the HTML you paste elsewhere is clean and consistently indented.
• Working with data alongside your markup? Pair this with the JSON Formatter. Writing docs instead of raw HTML? Try the Markdown Preview.
• For a deeper walkthrough, read How to Preview HTML Online.