HTML Online Runner

HTML Online Runner is a streamlined web-based tool designed specifically for instantly executing and visually verifying HTML, CSS, and JavaScript code. Users simply input valid markup or script, and the tool renders the live webpage output directly in an embedded preview frame—no local setup, build tools, or server required.

• Primary Purpose: This tool excels at rapid validation of page structure, styling, or interactive behavior. Common use cases include classroom demonstrations, coding interview exercises, snippet testing, and responsive layout previews. All execution occurs securely within the browser’s sandbox, with no data sent to external servers.
• Key Features: Offers a toggleable real-time preview mode or manual run trigger; includes formatting (to beautify code) and compression (to minify whitespace and line breaks); provides one-click clear, copy, and download options for code reuse; and supports undo/redo for safe experimentation.
• How It Works: Paste or type HTML (with optional CSS/JS) into the input area. The preview updates automatically (if real-time mode is on) or upon clicking “Run.” The “Run in New Window” button opens the current code in a separate browser tab—useful for full-screen testing or checking behavior in an isolated context.
• Target Users: Ideal for students, educators, front-end developers, and technical interviewers who need to quickly test, demonstrate, or share executable web code without complex tooling.

HTML Online Runner emphasizes simplicity and immediacy—focusing solely on running and visualizing web content. Its clean interface and fast feedback loop make it a go-to utility for lightweight, browser-based web validation.