Chrome extension documentation

A11Y Cat Extension

A local-first Chrome extension for active-page accessibility review. It runs packaged checks after a toolbar action, separates confirmed issues from review evidence, and exports handoff-ready QA reports.

Manifest V3 No host permissions Packaged runtime Manual review still required

Install locally Browse features Store materials

Public media shows the extension panel only. Automated and guided output supports human review; it does not certify WCAG conformance or replace manual accessibility testing.

A11Y Cat Extension panel body with Scan Results open. — Current build screenshot: Scan Results with confirmed issues, review state, filters, and coverage gaps.

Quick access

Install and testLoad the extension package, run a smoke scan, and check browser support boundaries.Understand resultsConfirmed issues, needs-review evidence, advisory signals, limitations, and diagnostics.Privacy and local dataWhat is processed locally, what is stored, what is exported, and what is not transmitted.SupportHow to report issues with safe evidence and without exposing sensitive page data.

Current extension surfaces

The video below shows current extension-panel surfaces only. It is a documentation aid, not a claim about any specific website.

Extension workflow video with native playback controls. Playback starts only when the user presses play.

Feature coverage

Scan Results

Runs current-page checks, groups confirmed issues separately from review items, exposes filters, issue details, highlight actions, and export controls.

View screenshot

Metadata Check

Reviews title, description, canonical URL, Open Graph, Twitter card, schema, and title/H1 alignment as review evidence where appropriate.

View screenshot

Headings

Checks semantic headings, visible H1 structure, skipped levels, ARIA headings, hidden headings, and visual heading-like text without markup.

View screenshot

Alt Text Analysis

Separates deterministic image failures from context-dependent review for decorative, linked, SVG/icon, complex, redundant, and background-image cases.

View screenshot

Language and Links

Provides language mismatch review and same-origin broken-link evidence while labelling incomplete or blocked checks as limitations.

View language screenshot View link-check screenshot

Browser Preference QA

Supports zoom, text spacing, font size, reduced motion, colour scheme, forced colours, and contrast-preference review as manual QA evidence.

View screenshot

Screen Reader Review

Uses bundled Guidepup virtual screen-reader support and browser TTS playback where available. It is review evidence, not real AT validation.

View screenshot

History, comparison, and exports

Stores local scan history, supports comparison and workflow notes, and creates user-controlled CSV, JSON, diagnostics, and HTML QA report exports.

Read result model

Technical implementation

Extension model

Manifest V3 package with a background service worker, packaged content runtime, local vendor dependencies, toolbar action, and keyboard command.

Page access

The extension uses activeTab and scripting after user action. It does not declare broad host permissions in the release manifest.

Local processing

Runtime checks execute in the browser against the active rendered page. The packaged build includes local axe-core and virtual screen-reader browser support.

Local storage

chrome.storage.local stores settings, scan history, archive state, workflow notes, performance history, and virtual review state on the browser profile.

Debugger-backed features

debugger is used for desktop/mobile emulation and selected browser preference media emulation. Core scanning still needs user-triggered page access.

Evidence boundary

Confirmed, review, advisory, limitation, and diagnostic outputs stay separate. Virtual screen-reader output is never presented as proof from NVDA, JAWS, VoiceOver, TalkBack, or Narrator.

Documentation map

How it worksToolbar click, activeTab access, packaged runtime, local checks, classification, storage, and exports.Scanner toolsModule inventory, evidence sources, output categories, and known boundaries.Feature guideVisible workflows, controls, evidence values, and release limitations.Privacy and local dataLocal-first processing, browser storage, exports, clearing controls, and privacy boundaries.Known limitationsWhat the extension cannot inspect, prove, or certify without additional human review.Chrome Web Store prepStore-ready copy, privacy answers, permission justifications, and screenshot asset status.

Result classification

Classification	Meaning	Primary action
Confirmed issue	High-confidence issue evidence for the current rendered state, usually from axe-core or strict A11Y Cat checks that pass reliability gates.	Remediate, retest, and confirm user impact in context.
Needs review	Evidence that needs human judgement, visual inspection, interaction, or assistive technology testing before it becomes a defect.	Inspect manually and record the decision before reporting it as a failure.
Advisory	Helpful quality, metadata, language, spelling, or review-readiness signal.	Use as guidance. Do not count it as a definite WCAG failure.
Limitation	A known boundary of what the extension could not inspect, calculate, or prove.	Use another method for the uncovered state and avoid coverage overclaims.
Diagnostic	Technical support information about permissions, injection, storage, runtime, exports, or scan coverage.	Use for troubleshooting and traceability. Do not treat it as a page failure.

Release boundary

A11Y Cat Extension supports accessibility review and remediation workflows. It does not certify production readiness, prove WCAG conformance, detect every issue, or replace manual accessibility and assistive technology testing.