#097 · HTML Developer Tool

HTML Viewer

Render HTML safely inside a sandboxed preview and switch between source, beautified, rendered, and split-style output. Use device-width presets to inspect how markup behaves on desktop, tablet, and mobile without creating a separate local file.

Developer Input

HTML viewer settings

HTML source

<!doctype html><html><head><style>body{font-family:system-ui;padding:2rem}article{max-width:36rem;margin:auto}button{padding:.7rem 1rem}</style></head><body><article><h1>HTML Preview</h1><p>This markup is rendered in a sandboxed frame.</p><button>Example button</button></article></body></html>

View mode

Preview width

Trim outer whitespace Preserve source spacing Beautify when applicable Auto-run while typing

How to use this developer tool

Paste or type the source content in the main editor.
Choose the processing mode and adjust the tool-specific option.
Enable or disable the validation and live-processing options as needed.
Select the primary action, review the report and statistics, then copy or download the result.

What this developer tool does

Preview HTML in a sandboxed browser frame with source, beautified, rendered, desktop, tablet, and mobile viewing modes.

Parse and optionally beautify source → render in sandboxed iframe or summarize the resulting DOM.

All processing occurs locally in the browser. Review automated findings before using the result in production.

Example

The editor is preloaded with a working HTML Viewer example. Change the sample, select an option, and run the tool to compare the input with the generated output and report.

Tips for better output

Keep scripts disabled while reviewing untrusted HTML.
Use beautified mode to locate structural problems.
Test responsive behavior at several widths.

FAQ

How do I preview HTML code online?

Paste the markup and select Render HTML. It is displayed inside a sandboxed iframe on the same page.

Is the HTML preview sandboxed?

Yes. The preview iframe uses a sandbox that prevents supplied scripts from executing with normal page privileges.

Can I beautify HTML before viewing it?

Choose Beautified source to normalize indentation and display copy-ready formatted markup.

How do I preview HTML at a mobile width?

Enter a smaller percentage or pixel-oriented width using the preview setting and render again.

Can I inspect a DOM summary instead of rendering HTML?

Yes. DOM summary reports element, link, image, form, script, style, ID, and class counts.

Related developer tools

HTML Checker HTML Generator HTML Converter HTML Parser

HTML Viewer modules

Module	Details
Modes	Rendered, beautified, source, summary
Security	Sandboxed iframe
Responsive	Adjustable preview width
Download	.html

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