Developer

HTML Validator✓

Parse HTML and download a JSON report. Parser acceptance is not a complete HTML standards conformance audit.

Tools will load when you run.
Input method
HTML
0 characters

How to use HTML Validator

  1. Choose your HTML, plain text or paste text into the editor.
  2. Choose your HTML source or paste it into the editor and review the supported parser or engine.
  3. Run validation and review the HTML JSON report.

Process multiple files

Use a workflow to apply the same settings to each file.

Formats and requirements

Input formats
HTML, plain text
Output
JSON
Availability
Free in your browser and through the CLI
Files per operation
1
Browser file limit
8 MiB per file, 128 MiB total

What to expect

Checks syntax with a local parser. Does not check project types, imports, dependencies or runtime behavior. Markdown accepts ordinary prose; HTML and CSS parsing is not a standards conformance audit.

Do my files leave my device?

No. Thanks to advanced file-processing technology, your files are processed directly on your device, inside your browser. OneKit does not receive your input files or results. Required public processing libraries may download when you first use the tool.

File privacy and local processing →

Install OneKit

Keep OneKit in its own app window, with a shortcut on your device.