# (X)HTML5 Checker

> A small extension to validate the markup of current webpage

Canonical page: [https://chrome-stats.com/d/x-html5-checker](https://chrome-stats.com/d/x-html5-checker)

## Overview

- **ID:** `x-html5-checker`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** Francesco De Stefano
- **Category:** web-development
- **Daily users:** 87
- **Weekly downloads:** 7
- **Rating:** 3.33 / 5 (3 ratings)
- **Version:** 0.0.4resigned1
- **Last updated:** 2024-04-26
- **First published:** 2018-12-05
- **Size:** 31 KB
- **Data as of:** 2026-09-12
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/x-html5-checker/)

## Description

(X)HTML5 Checker is a lightweight Chrome extension designed to help web developers validate the HTML markup of their current webpage effortlessly. Leveraging the official W3C Validator web service APIs, it sends your page's HTML to ensure compliance with web standards. 

The extension highlights errors in a user-friendly popup, displaying the exact source code segments where issues are found, making it simple to detect and fix markup problems during development and maintenance. Ideal for maintaining clean, standard-compliant code, (X)HTML5 Checker streamlines the validation process without leaving your browser environment.

## Rankings

- #12,538 — Overall
- #58 — html
- #91 — checker
- #170 — error
- #188 — x

## Permissions and access

### Permissions

- `<all_urls>`
- `activeTab`

## Safety

- **Risk impact:** Moderate risk impact
- **Risk likelihood:** Low risk likelihood

### Analysis details

- Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
- 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).

## Similar extensions and apps

- [HTML Validator Plus](https://chrome-stats.com/d/html-validator-plus) — 16 users
- [Web Developer Checklist](https://chrome-stats.com/d/webdeveloperchecklist) — 669 users, 4.25 / 5
- [A1 HTML Checker](https://chrome-stats.com/d/a1-html-checker)
- [HTML Tag Error Checker](https://chrome-stats.com/d/html-tag-error-checker) — 80 users
- [a11y.css accessibility checker](https://chrome-stats.com/d/a11ycss) — 188 users, 5.00 / 5
- [Html Validator](https://chrome-stats.com/d/html-validator) — 6,088 users, 4.23 / 5
- [Code Compliance](https://chrome-stats.com/d/code-compliance) — 8 users, 5.00 / 5
- [Validate HTML](https://chrome-stats.com/d/validate-html-addon)
- [HTML, CSS, JS Validator](https://chrome-stats.com/d/html-css-js-validator) — 1 users, 1.00 / 5
- [Website Accessibility Ck](https://chrome-stats.com/d/website-accessibility-ck)
- [CSS Validation Checker](https://chrome-stats.com/d/css-validation-checker) — 6 users
- [CSS Diagnostics](https://chrome-stats.com/d/css-diagnostics) — 1 users

---

Source: [Chrome-Stats](https://chrome-stats.com/d/x-html5-checker)