Online HTML Viewer

Write HTML, CSS, and JavaScript in the editor and see the live output instantly. Your code is saved automatically — no signup required.

Ctrl+Enter to refresh

Live Preview

What is an Online HTML Viewer?

An online HTML viewer is a free browser-based code editor that renders your HTML, CSS, and JavaScript in real time without any installation, server, or local development environment. You write code on the left, and the live preview updates instantly on the right.

Calcon's HTML Viewer is ideal for learning web development, testing CSS snippets, prototyping UI components, and practicing JavaScript — all in one place.

How to Use the HTML Viewer

Select the HTML, CSS, or JS tab to switch between the three editors.
Type or paste your code. The live preview on the right updates automatically as you type.
Press Ctrl+Enter (or Cmd+Enter on Mac) to force a full iframe refresh — useful when JavaScript state needs resetting.
Click Copy to copy the complete HTML file to your clipboard.
Click Download to save your code as index.html — open it in any browser.
Click Clear to reset all three editors and start fresh.

Your code is automatically saved to browser localStorage after every change, so it persists if you refresh or close the tab.

Key Features

Live preview: The iframe updates on every keystroke — no refresh button needed.
Syntax highlighting: Powered by CodeMirror with GitHub Light theme for HTML, CSS, and JavaScript.
Auto-save: Code is persisted in localStorage between sessions.
Download as HTML: Export a self-contained .html file with your code embedded.
Sandboxed preview: JavaScript runs in a sandboxed iframe, keeping your browser session safe.
Keyboard shortcut: Ctrl+Enter forces a full preview reload.

Keyboard Shortcuts

Shortcut	Action
Ctrl + Enter	Force-refresh the preview iframe
Ctrl + A	Select all code in the active editor
Ctrl + Z	Undo last change
Ctrl + Shift + Z	Redo
Tab	Indent selected code (CodeMirror built-in)

What Can You Build?

HTML & CSS practice: Learn selectors, flexbox, grid, and animations with instant visual feedback.
UI prototypes: Quickly mock up a button, card, navbar, or form before adding it to your project.
JavaScript experiments: Test DOM manipulation, event listeners, fetch API calls, and animations.
Interview prep: Practice HTML/CSS/JS coding challenges with live feedback, just like in a technical interview.
Bug isolation: Copy a buggy snippet from your project into the viewer to isolate and debug it cleanly.

Frequently Asked Questions

Is this HTML viewer free to use?

Yes, completely free. No signup, no login, and no usage limits. Open the page and start writing HTML immediately.

Where is my code saved?

Your code is automatically saved to your browser's localStorage. It persists between sessions and is never sent to any server. You can also download your code as an .html file using the Download button.

Does the HTML viewer support JavaScript?

Yes. The HTML viewer supports HTML, CSS, and JavaScript. The preview runs your JavaScript inside a sandboxed iframe for security, which means most standard JavaScript features work.

How do I force-refresh the preview?

Press Ctrl+Enter (or Cmd+Enter on Mac) to force a full reload of the preview iframe. This is useful when JavaScript state needs to be reset.

Can I download my code?

Yes. Click the Download button to save your combined HTML, CSS, and JavaScript as a single index.html file that you can open in any browser.

Does this work on mobile?

Yes, the HTML viewer works on smartphones and tablets. The layout switches to a stacked view on smaller screens so both the editor and preview remain usable.

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