Free Online HTML Viewer & Previewer — Paste HTML Code and See It Render Live

HTML
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All live, all free, all browser-only. No signup, no limits.

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01
Currently using
HTML Viewer
Paste HTML from Claude, ChatGPT, or your editor — see it render live. Device frames, share links, zero setup.
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02
Live
Markdown Editor
Write markdown, see clean semantic HTML render next to it. Light and dark preview. Copy the HTML out in one click.
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03
Live
HTML → PDF
Render HTML to a print-perfect PDF in one click. Respects @page rules, headers, footers, page breaks.
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04
Live
JSON Viewer
Paste minified, deep, or messy JSON — read it as a collapsible tree. Format, minify, copy. Browser-only.
Open →
about

A free online HTML viewer.
Paste, render, share.

HTML Viewer Cat is a free online HTML viewer that renders raw HTML live in a sandboxed iframe — paste, see it render, share via URL fragment. Works with Claude, ChatGPT, Cursor output, email templates, React snippets, anything you can paste. Nothing is sent to a server.

Use it for debugging Claude or ChatGPT HTML output before pasting it into a real codebase, previewing an email-template snippet across desktop, tablet, and phone widths, sanity-checking what a React component actually renders to in the DOM, or sharing a quick mockup with a designer by sending them a fragment URL — no account, no upload, no expiring preview link.

The editor is a full CodeMirror instance with syntax highlighting, bracket matching, line numbers, and Cmd/Ctrl+Z undo. The preview is a sandboxed iframe with allow-scripts on so interactive components work, but allow-top-navigation off so a pasted snippet can't redirect your tab. The split between editor and preview is draggable and remembers its position; drafts auto-save to your browser's localStorage so closing the tab doesn't lose your work.

What it doesn't do: no "save to cloud", no shared workspaces, no collaborative cursors, and the share-URL fragment caps at about 2KB before browsers complain. If you want the same shape for prose, the Markdown editor renders Markdown to HTML in a parallel pane. Why these tools. Full FAQ.

frequently asked

HTML viewer
questions, answered.

Full FAQ →
A tool that renders raw HTML without requiring you to save a file and open it in a browser. Paste code in, see the result immediately.
No. Everything runs in your browser in a sandboxed iframe. We don't have a backend that sees your HTML. Your last draft is saved to localStorage on your own device.
Yes. Click Share — your HTML is encoded into the URL, so anyone who opens the link sees exactly what you see. No account required.
Yes, inside a sandboxed iframe with restricted permissions. Parent-window access is blocked for safety.
Yes. Switch between desktop, tablet, and phone viewports at the top-right of the preview pane.
Completely free. No ads on the tool itself, no account, no limits.