(X)HTML5 Checker

Name: (X)HTML5 Checker
Rating: 3.3333 (3 reviews)
Author: Francesco De Stefano

By: Francesco De Stefano

A small extension to validate the markup of current webpage

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Features & Capabilities

(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.

User Growth & Download Statistics

Add-on Developer Tools Education

By:

Daily users:

Rating:

Version:

0.0.4resigned1 Last updated: 2024-04-26

Version code:

5732429

Creation date:

2018-12-05

Risk:

Permissions:

<all_urls>
activeTab

Size:

30.55KB

Email:

ul*****@mediamaster.eu

Full description:

Source:

Firefox Add-ons Store

Data ingested on:

2026-06-19

Compare stats and ranking:

Ranking

# 12,520 ▼ 80

Other rankings

#51 in html keyword 41 #93 in checker keyword 69 #176 in x keyword 39 ▼ 2

For Developers

Monetize with App Pass Boost with Extension Booster

Contact the developer

Chrome-Stats does not own this Firefox add-on. Please use these information below to contact the Firefox add-on developer.

Developed by:

Francesco De Stefano

Firefox Add-ons Store

https://addons.mozilla.org/firefox/addon/x-html5-checker/

Email:

ul*****@mediamaster.eu

User Reviews

by 退出*****, 2025-04-02

by 退出*****, 2025-03-03

I tried it briefly and disabled it. It cannot send the code of a page from my local/development server to the W3C validator. It's only useful for pages that are already live-online (public), but that's not when I do my code validation; I check my code while it's still in development. You might think it's impossible to send non-public code to the W3C validator, but I do it all the time (by Command-U to see the browser's parsed/rendered code, copy all, go to W3C, and paste into their validator). If I can go through these steps, why can't this extension do that for me? Another (minor) problem is that there doesn't seem any way to have this extension put an icon in the Firefox toolbar, like my other extensions do. (Yes I know how to customize the toolbars.) This extension seems to be only accessible by pulling down the Extensions sub-menu. Not worth the trouble. Disabled.

by La*****, 2023-12-14

View all user reviews ›

Is (X)HTML5 Checker Safe?

Risk impact

Risk impact measures the level of extra permissions an extension has access to. A low risk impact extension cannot do much harms, whereas a high risk impact extension can do a lot of damage like stealing your password, bypassing your security settings, and accessing your personal data. High risk impact extensions are not necessarily malicious. However, if they do turn malicious, they can be very harmful.

(X)HTML5 Checker requires a few sensitive permissions. Exercise caution before installing.

Risk impact analysis details

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

Risk likelihood

Risk likelihood measures the probability that a Firefox add-on may turn malicious. This is determined by the publisher and the Firefox add-on reputation on Firefox Add-ons Store, the amount of time the Firefox add-on has been around, and other signals about the Firefox add-on. Our algorithms are not perfect, and are subject to change as we discover new ways to detect malicious extensions. We recommend that you always exercise caution when installing a Firefox add-on.

(X)HTML5 Checker has earned a fairly good reputation and likely can be trusted.

Risk likelihood analysis details

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