| CSS HTML Validator | |
|---|---|
 CSS HTML Validator Pro | |
| Developer | AI Internet Solutions LLC |
| Stable release | 2025 (v25.01) / January 7, 2025; 10 months ago (2025-01-07) |
| Operating system | Windows 10 and later |
| Type | HTML editor |
| License | Trialware |
| Website | www |
CSS HTML Validator (previously namedCSE HTML Validator) is anHTML editor andCSS editor forMicrosoft Windows (andLinux and otherUnix-like operating systems when used withWine) that helps web developers create syntactically correct andaccessibleHTML/HTML5,XHTML, andCSS documents by locating errors, potential problems like browser compatibility issues, and common mistakes. It is also able to check links, check spelling, suggest improvements, alert developers to deprecated, obsolete, or proprietary tags, attributes, and CSS properties, and find issues that can affectsearch engine optimization.
CSS HTML Validator is developed, marketed, and sold by AI Internet Solutions LLC located inTexas.[1] The first version of CSS HTML Validator was released in 1997 forWindows 95. The current version is 2025/v25.01[2] (as of January 24, 2025) and is forWindows 10 and above, includingWindows 11. A nativemacOS andLinux command line version (called htmlval) became available with version 23. There are currently three main editions of CSS HTML Validator — Pro/Professional, Home/Standard, and Lite. The Enterprise edition was discontinued in 2025/v25. While the application is generally a commercial product (except for the Lite edition), a free version of the Home edition is available for personal/educational, non-commercial use. A free limited version of the htmlval command line tool for macOS and Linux is also available.
CSS HTML Validator includes anHTML editor,validator forHTML,XHTML,htmx,polyglot markup,CSS,PHP andJavaScript (usingJSLint orJSHint), link checker (to finddead and broken links),spell checker,accessibility checker, andsearch engine optimization (SEO) checker. An integrated web browser allows developers to browse the web while the pages are automatically validated.
Because documents are checked locally and not uploaded over the Internet to a server in order to be checked, validations are performed relatively quickly, and security and privacy are increased.
A custom scripting language called TNPL, included in the Pro and Enterprise editions, can be used to customize validations by adding, eliminating, or changing validator messages. TNPL can also be used to integrate customized validation checks to meet the unique requirements of an individual or entity.
A Batch Wizard tool, included in the Pro and Enterprise editions, can check entire Web sites, parts of Web sites, or a list of local web documents. The Batch Wizard generates reports in standard HTML or XML format. The reports can be viewed using a normal web browser.
The accessibility checker includes support forSection 508 Amendment to the Rehabilitation Act of 1973 andWeb Content Accessibility Guidelines (both WCAG 1.0 and WCAG 2.0/2.1/2.2).
Using a version ofHTML Tidy with HTML5 support and the Pretty Print & Fix Tool, CSS HTML Validator can automatically fix some common problems withHTML andXHTML documents. However, some problems cannot be fixed (or fixed correctly) with automated tools and require manual review and repair.
Validation ofpolyglot markup was added in version 12, and mobile development support (for HTML and CSS) was added in version 14 and improved in version 15. Version 15 added built-in syntax checking forJSON andHTML5 cache manifest files. Version 16 added JavaScript linting usingJSHint, a static code analysis tool for checking JavaScript, but also continues to supportJSLint. Version 17 added support for theAccelerated Mobile Pages Project, which is a type of HTML optimized for mobile web browsing, and support for live DOM validation usingGoogle Chrome[3]
CSS HTML Validator 2018/v18 renames the software from CSE HTML Validator to CSS HTML Validator and includes updated HTML5 and CSS support. Version 18 also added a new "By Message" report in the Batch Wizard and dropped support forWindows Vista and below.
CSS HTML Validator 2019/v19 includes updated HTML and CSS support, adds WCAG 2.1 support, improves support when running underWine (software), and is a native 64-bit application (previously releases were 32-bit). CSS HTML Validator 2020/v20, first released in January 2020, includes HTML, CSS, accessibility, and other updates, including improved support for theAccelerated Mobile Pages Project. Also, beginning with version 20, the Standard edition was renamed to the Home edition.
CSS HTML Validator 2021/v21, first released in January 2021, includes further HTML, CSS, accessibility, and other updates.
CSS HTML Validator 2022/v22, released in January 2022, includes improvements and updates to keep the program up-to-date, a new Microsoft Edge WebView2 rendering engine for the integrated web browser, and three new dark themes. Later updates to version 22 added support for checkingJSON Lines andNDJSON documents.
CSS HTML Validator 2023/v23, released in January 2023, includes more improvements and updates to keep the program up-to-date. The new release also introduced new command linemacOS andLinux ports of the core validation engine, called htmlval for Mac and Linux.[4] Official support for Windows 7, 8, and 8.1 was dropped in the 2023/v23 version.
CSS HTML Validator 2024/v24, released in January 2024, includes updates and improvements. It also adds support forhtmx.
CSS HTML Validator 2025/v25, released in December 2024 and still the current major release, includes further updates and improvements for 2025. Version 25 discontinues the Enterprise edition, moving Enterprise functionality to the Pro edition.
An online edition based on CSS HTML Validator Pro that can check documents via file upload, URL, or snippets (direct text input) was discontinued May 2017 in favor of the desktop version for Microsoft Windows.
The purpose of validation and computerized checking of HTML, XHTML, and CSS documents is to help make sure that the documents are syntactically correct and problem-free. Checked HTML, XHTML, and CSS documents are more likely to:
While automated checking tools are helpful for website development and continued maintenance, they cannot guarantee that a document will display (render) and behave as intended in all browsers. Developers should always test documents in a variety of browsers (including mobile browsers) to locate problems that cannot be detected with a computerized checking tool.
CSS HTML Validator integrates with other third-party software like those listed below. This allows validation using CSS HTML Validator from within the third-party program.
