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HTML Formatter & Viewer

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Formatted Output0 bytes / 0 lines / Depth: 0
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This tool is provided as-is for convenience. Output should be verified before use in any production or critical context.

Programmatic Access

HTML Formatter & Viewer is also callable as a free HTTP JSON API at https://aidevhub.io/api/html-formatter/ — GET with query parameters or POST with a JSON body, no authentication, CORS enabled, 50 requests/day per IP. Responses return { ok, tool, result, meta }. 

curl -s -X POST https://aidevhub.io/api/html-formatter/ \
  -H "Content-Type: application/json" \
  -d '{"html":"<div><p>Hello</p><span>world</span></div>","mode":"format"}'

Machine-readable contract: /api/tool/html-formatter.json All API endpoints: /agents/ LLM site index: /llms.txt

Agent Invocation

Best Path For Builders

Dedicated API endpoint

Deterministic outputs, machine-safe contracts, and production-ready examples.

Dedicated API

https://aidevhub.io/api/html-formatter/

OpenAPI: https://aidevhub.io/api/openapi.yaml

GET /api/html-formatter/ GET html-formatter
POST /api/html-formatter/ POST html-formatter

Unified Runtime API

https://aidevhub.io/api/tools/run/?toolId=html-formatter&a=...

GET and POST are supported at /api/tools/run/ with identical validation and limits.

Limit: 30 req / 60s, input max 256 KB.

How to Use HTML Formatter & Viewer

  1. 1

    Paste your HTML

    Copy your HTML code (minified or unformatted) into the textarea. Handles HTML fragments and complete documents.

  2. 2

    View formatted output

    Formatted HTML appears instantly in the right panel with proper indentation, line breaks, and spacing. Syntax highlighting shows structure.

  3. 3

    Check for errors

    View error count at the top. Errors show with line numbers and messages (unclosed tags, invalid nesting, deprecated elements).

  4. 4

    Copy or download

    Click 'Copy' to copy formatted HTML to clipboard. Click 'Download' to save as .html file for your project.

Frequently Asked Questions

What is HTML Formatter & Viewer?
HTML Formatter & Viewer formats, beautifies, and validates HTML with live preview and syntax highlighting. It also supports minification for production-ready output.
How do I use HTML Formatter & Viewer?
Paste your HTML into the editor and click Format to beautify it or Minify to compress it. Use the live preview panel to see how the HTML renders, and check the validation output for any issues.
Does HTML Formatter & Viewer store or send my data?
No. All processing happens entirely in your browser. Your HTML code never leaves your device — nothing is sent to any server.
Does it validate HTML for errors?
Yes. The tool checks for common HTML issues like unclosed tags, missing attributes, and improper nesting. It highlights problems in the editor so you can fix them before deploying.