# squizlabs/HTML_CodeSniffer

HTML_CodeSniffer is a client-side JavaScript application that checks a HTML document or source code, and detects violations of a defined coding standard. Comes with standards that cover the three conformance levels of the W3C's Web Content Accessibility Guidelines (WCAG) 2.0 and the U.S. Section 508 legislation.

Repository: https://github.com/squizlabs/HTML_CodeSniffer
Canonical: https://ross.abutalabs.com/products/html_codesniffer
Homepage: https://squizlabs.github.io/HTML_CodeSniffer/
Language: JavaScript
License: BSD-3-Clause
License Family: permissive
Last push: 2024-01-07T19:25:06+00:00

## Health v2 (maintenance only)
Score: 23/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 5431, "days_push": 969, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1146, forks 253 (observed 2026-08-28T04:03:45.773175+00:00)

## What it is
HTML_CodeSniffer is a client-side JavaScript library that checks HTML documents or source code for violations of defined coding and accessibility standards, including WCAG 2.1 (Levels A, AA, AAA) and U.S. Section 508. It can be called from JavaScript, run via a bookmarklet auditor, used as an npm module, or executed on the command line with a headless browser.

## Use cases
- audit a web page for WCAG 2.1 accessibility violations
- check HTML source code against Section 508 standards
- run automated accessibility checks in a headless browser from the command line
- enforce custom HTML coding standards across a website with custom sniffs
- quickly inspect any page's accessibility issues with a bookmarklet
- integrate HTML accessibility linting into a Node.js build pipeline

## When to choose
- you need client-side, server-free HTML accessibility auditing
- you need WCAG 2.1 or Section 508 conformance checks out of the box
- you want a bookmarklet for quick manual audits of live pages
- you need to define custom HTML coding standards via sniffs

## When to avoid
- you need full-page automated testing with modern tooling like axe-core or Lighthouse
- you need server-side rendering checks or non-HTML document formats
- you require actively developed tooling with frequent updates

## Facets
- artifact type: library
- maturity: maintenance
- function: testing, accessibility, linter, browser-extension
- domain: web-development, accessibility, developer-tools, testing
- platform: browser, cli
- tags: wcag, section-508, html-auditing, bookmarklet, a11y-testing, nodejs, javascript

## Member repositories
- squizlabs/HTML_CodeSniffer (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:45.773175+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:34:12.777335+00:00, confidence not recorded.
  - readme: https://github.com/squizlabs/HTML_CodeSniffer (fetched 2026-08-28T04:03:45.773175+00:00, sha 9799fb6a35ed)
  - homepage: https://squizlabs.github.io/HTML_CodeSniffer/ (fetched 2026-08-29T12:39:43.472945+00:00, sha ab76c1eed1df)
  - registry_npm: https://registry.npmjs.org/html_codesniffer (fetched 2026-08-29T12:39:43.481976+00:00, sha 6382a226c376)
- Data as of 2026-08-30T08:39:29.467469+00:00.