HTML Preview

How to Use the HTML Preview Tool

This free online HTML previewer lets you write HTML, CSS, and JavaScript code and see the results instantly in a sandboxed iframe. Enter your code in the left panel and click "Run" to render it in the preview panel on the right. The preview is safely sandboxed to prevent any interference with the main page.

Features

• Live HTML/CSS/JavaScript preview in a sandboxed iframe
• Split-panel layout for side-by-side editing and viewing
• Sample HTML template with CSS styling and JavaScript interactivity
• Safe execution environment with sandbox restrictions
• No server-side processing - everything runs in your browser

Use Cases

This tool is perfect for quickly testing HTML snippets, prototyping UI components, learning HTML/CSS/JS, debugging layout issues, and sharing code examples. It works like a simplified version of CodePen or JSFiddle, but runs entirely in your browser without requiring any account or setup.

Security

The preview iframe uses the sandbox attribute which restricts potentially dangerous operations. Scripts are allowed to run within the sandbox for interactive previews, but they cannot access the parent page, make network requests to external servers, or access your browser storage. Your code never leaves your browser.

HTMLプレビューツールについて

HTML、CSS、JavaScriptを入力してリアルタイムでプレビュー表示できるツールです。サンドボックス化されたiframe内で安全に実行されるため、メインページへの影響はありません。UIプロトタイプやコードスニペットのテストに便利です。