Code Validators
Before publishing or deploying any web project, it is good practice to validate your code. The three tools below help you catch errors early, improve accessibility, and keep your site standards-compliant.
Markup Validation
HTML Validator
The W3C Markup Validation Service checks your HTML (and XHTML) documents against official web standards. It finds missing tags, incorrect nesting, deprecated attributes, and other structural problems that can break pages in browsers or hurt accessibility and SEO.
Use it whenever you create or edit a page to make sure the markup is clean and valid.
Stylesheet Information
CSS Validator
The W3C CSS Validation Service examines your Cascading Style Sheets for syntax errors, unknown properties, invalid values, and other issues. Valid CSS helps ensure consistent rendering across browsers and makes your stylesheets easier to maintain.
You can validate a stylesheet by URL, by file upload, or by pasting the CSS directly.
Server-Side Code Check
PHP Syntax Checker
PHP does not have an official W3C-style validator, but online syntax checkers can quickly detect missing semicolons, unclosed brackets, mismatched quotes, and other parse errors before you upload code to a server.
These tools are especially useful for spotting simple mistakes that would otherwise produce a blank page or a fatal error.