w3c-nu-validator 0.1.1

CLI tool to validate deployed URLs via the W3C Nu HTML Checker (JSON output).

w3c-nu-validator

A lightweight Python CLI tool for validating deployed URLs using the W3C Nu HTML Checker HTTP API (JSON output).

This tool is designed to validate the HTML that users and assessors actually see in production, rather than local templates or development builds.

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Why this exists

Manual HTML validation via copy-pasting URLs into the W3C validator is:

• slow
• repetitive
• error-prone
• difficult to repeat consistently across many pages

This tool allows you to:

• validate many deployed URLs in one run
• capture a complete, site-wide validation report
• fix issues systematically instead of page-by-page

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Features

• Validate one or more deployed URLs
• Read URLs from a file (one per line)
• De-duplicate URLs automatically
• Write a full validation report to disk
• Return a meaningful exit code (useful for scripts / CI)
• Uses the official W3C Nu Validator HTTP interface

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Installation

From PyPI

pip install w3c-nu-validator

This installs the w3c-nu-validator command.

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Editable Install

Clone the repository and install it into a virtual environment.

pip install -e .

Or install from another project in editable mode:

pip install -e /path/to/w3c-nu-validator

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Usage

Validate one or more URLs

w3c-nu-validator https://example.com https://example.com/about/

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Read URLs from a file

w3c-nu-validator -r urls.txt

File rules:

• one URL per line
• blank lines are ignored
• lines starting with # are ignored

Example urls.txt:

[!NOTE] Lines beginning with hash # marks are treated as comments and thus ignored.

# Home page
https://example.com/

# Resource list
https://example.com/resources/

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Write a full report to a file

w3c-nu-validator -r urls.txt -o report.txt

The report includes:

• a delimiter per URL
• error / info counts
• full error messages with HTML extracts

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Exit codes

Code	Meaning
0	No validation errors found
1	One or more URLs contain validation errors
2	Invalid input (missing URLs, unreadable file, etc.)

This allows quick pass/fail checks:

w3c-nu-validator -r urls.txt
echo $?

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Requirements

• Python 3.10+
• requests

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Licence

MIT Licence.

This project is provided as-is, without warranty. See the LICENSE file for details.