💻 Developer Tools

HTML Viewer & Preview

Paste HTML code and instantly preview the rendered result in a live iframe — test responsive designs at multiple viewport widths.

How the HTML Viewer works

Paste any HTML snippet or full page into the editor and click Run / Preview. The HTML is rendered in a sandboxed iframe using the srcdoc attribute, so embedded <style> and <script> tags work normally. Switch between Mobile, Tablet, Desktop, or Full viewport widths to test responsive layouts.

Why the HTML Viewer is Useful

Previewing and testing HTML code without a local development environment is something every developer, learner, and template buyer needs. Whether you're checking if an HTML email renders correctly, testing a snippet copied from documentation, previewing a component, or learning HTML by watching live output as you type, this viewer renders your code — including embedded CSS and JavaScript — with multiple viewport widths for responsive testing.

Key Features

  • Sandboxed HTML rendering: Full HTML including embedded CSS and JavaScript rendered in an isolated iframe
  • Responsive testing: Switch between Mobile (375px), Tablet (768px), Desktop (1024px), and Full viewport modes
  • Side-by-side layout: Code editor on the left, live preview on the right for fast iteration
  • Copy HTML button: Copy your code to clipboard with one click
  • No installation required: Works entirely in the browser, nothing to set up

Real-Life Use Cases

  • Previewing HTML email templates before sending to a subscriber list to check layout and rendering
  • Learning HTML and CSS by writing code and seeing exactly how it renders in a browser in real time
  • Testing code snippets from Stack Overflow, documentation, or AI-generated responses before using in a project
  • Designers previewing HTML/CSS components exported from Figma or copied from a component library
  • Quickly rendering a template received from a client or vendor without setting up a full development environment

Who Can Use This Tool

Web developers, HTML/CSS beginners and learners, email marketers, UI designers, front-end engineers, QA testers, and anyone who needs to quickly preview or test an HTML snippet without a local development setup.

Tips & Best Practices

  • Always test your layout in Mobile view first — the majority of web traffic now comes from phones
  • Paste the full <html> document including the <head> for accurate rendering of Google Fonts and CSS resets
  • The sandbox attribute limits some browser APIs — external fetch calls and localStorage won't work in the preview
  • For debugging layout issues, temporarily add border:1px solid red; to elements to see their exact dimensions and positioning

Frequently Asked Questions

How do I view HTML code online?
Paste your HTML code into the editor above and click "Run / Preview". The rendered result appears instantly in the iframe on the right.
Can I test responsive designs with different screen sizes?
Yes. Use the viewport selector to switch between mobile (375px), tablet (768px), desktop (1024px), or full width. The preview iframe resizes automatically.
Does this tool support CSS and JavaScript?
Yes. Any inline and tags inside your HTML are rendered along with the markup, so full pages with embedded CSS and JavaScript work correctly.
How is the HTML rendered?
The HTML is injected into an iframe using the srcdoc attribute, which isolates the preview from the parent page and provides a clean rendering environment.
Is the HTML Viewer free to use?
Yes, the HTML Viewer on Potential Daily is completely free with no sign-up required.
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