Tool Information
The CSS Validator is an essential tool for writing clean, efficient, and cross-browser compatible code, improving website performance. It allows you to validate your CSS stylesheets to ensure they are free of syntax errors and follow best practices. CSS (Cascading Style Sheets) is a style sheet language used for describing the presentation of a document written in a markup language such as HTML. Our validator makes it easy to check your CSS for errors, so you can be confident that your stylesheets are valid and that they will be applied correctly by all web browsers. The tool is designed to be fast and accurate, and it can validate any CSS stylesheet. It provides you with clear and helpful error messages, so you can quickly identify and fix any issues in your CSS. By using our validator, you can save time and effort, and you can prevent errors that can arise from invalid CSS. Our CSS Validator is a must-have tool for any web developer. It is a simple yet powerful tool that can have a big impact on the quality of your website. By using our validator, you can create more professional and maintainable websites, and you can ensure that your designs are always displayed as intended.
CSS Validator
Check your CSS for syntax errors and invalid rules. Validation runs 100% in your browser — no code leaves your machine.
How to Use the CSS Validator
- Paste your CSS code into the left editor.
- Click Validate to run syntax checks and rule parsing in your browser.
- Review the Errors (invalid rules) and Warnings (possible issues).
- Use the copy or download buttons to export the report.
What the validator checks
- • Basic bracket/parenthesis balance (warnings)
- • Missing semicolons inside rule blocks (heuristic warnings)
- • Invalid CSS rules detected by attempting to insert each rule into the browser's stylesheet (errors)
- • The validator is syntax-aware but not a full linter — it won't flag stylistic or best-practice issues.
💡 Privacy note: Validation is performed entirely in your browser — the code never leaves your machine.
What is a CSS Validator?
A CSS Validator is a tool that checks your Cascading Style Sheets (CSS) code for syntax errors and compliance with web standards. It helps you find mistakes like typos, incorrect property names, or invalid values, ensuring that your stylesheets are well-formed and will be correctly interpreted by web browsers.
Why Use Our CSS Validator?
- Error Detection: Quickly identify and fix syntax errors that could break your website's layout or appearance.
- Browser Compatibility: Writing valid CSS helps ensure that your site looks consistent across different browsers.
- Best Practices: Encourages you to write clean, standard-compliant code, which is easier to maintain and debug.
- Learning Tool: Helps you learn the correct CSS syntax and rules by pointing out your mistakes.
🚀 Explore More Free Developer Tools
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Minify CSS code by removing whitespace and comments
🎨 SCSS Validator
Validate SCSS stylesheets
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