# A1 HTML Checker

> Run a fast local markup structure check on the active page with selectors and snippets.

Canonical page: [https://chrome-stats.com/d/a1-html-checker](https://chrome-stats.com/d/a1-html-checker)

## Overview

- **ID:** `a1-html-checker`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** A1 Local Extensions
- **Category:** web-development
- **Version:** 0.1.0
- **Last updated:** 2026-05-27
- **First published:** 2026-05-24
- **Size:** 31 KB
- **Data as of:** 2026-09-12
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/a1-html-checker/)
- **Website:** [https://a1local.com.au/extensions/support/](https://a1local.com.au/extensions/support/)
- **Privacy policy:** [https://addons.mozilla.org/firefox/addon/a1-html-checker/privacy/](https://addons.mozilla.org/firefox/addon/a1-html-checker/privacy/)

## Description

A1 HTML Checker helps developers, SEOs, and site owners spot common rendered-DOM structure issues without sending page content to a remote validator. Click the extension, run a check, and review findings with selectors and snippets where feasible. It checks duplicate IDs, empty href and src values, missing html lang and title, missing image alt text, heading jumps, form labels, and common invalid nesting heuristics.

## Rankings

- #147,292 — Overall

## Permissions and access

### Permissions

- `activeTab`
- `scripting`
- `storage`

## Safety

- **Risk impact:** Very low risk impact
- **Risk likelihood:** High risk likelihood

### Analysis details

- This extension has low user count. Unpopular extensions may not be stable or safe.

> Some risk analysis details are omitted from this free response. [Upgrade to view the full analysis](https://chrome-stats.com/pricing).

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Source: [Chrome-Stats](https://chrome-stats.com/d/a1-html-checker)