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CSS Formatter Online — Free CSS Beautifier, Minifier & Validator

CSS Formatter

Format, minify, and validate CSS with sorting and SCSS conversion.

Free online CSS formatter and beautifier. Paste your CSS, choose indentation style (2 or 4 spaces, tabs), and format instantly. Minify CSS for production use, validate syntax with error detection, convert CSS to SCSS syntax, sort properties alphabetically, or add vendor prefixes automatically. Extracts and lists all custom properties (CSS variables). Formats embedded CSS in HTML and JSX automatically. Runs entirely in your browser — no data is ever sent to a server.

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Tags: css, format, beautify, minify, validate, prettify, scss, autoprefixer

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How to CSS Formatter Online

  1. Paste your CSS into the input area on the left, or upload a .css file using the upload button. You can also drag and drop a file directly onto the input area.

  2. Choose your indentation style — 2 spaces, 4 spaces, or tabs — to match your team's coding standards.

  3. Optionally enable Sort Properties to alphabetically order CSS properties within each rule for consistent, diff-friendly output.

  4. Click the Format button or press ⌘↵ (Mac) / Ctrl+Enter (Windows) to beautify your CSS instantly with syntax highlighting.

  5. Use Minify to collapse the CSS to a single line for production embedding, Validate to check for syntax errors, → SCSS to convert to Sass syntax, Sort Props for alphabetical ordering, or Autoprefix to add vendor prefixes.

  6. Copy the formatted output with ⌘⇧C, download it as a .css file, or use the Share button to generate a gzip-compressed shareable URL.

CSS Formatter Features

  • CSS formatter with configurable indentation: 2 spaces, 4 spaces, or tabs to match your team's coding standards.

  • Sort Properties option: alphabetically reorders all CSS properties within each rule for consistent, diff-friendly, and code-review-friendly output.

  • CSS minifier: collapses formatted CSS to a single line by removing whitespace and comments for production use.

  • CSS validator with syntax error detection: unbalanced braces, invalid property syntax, missing semicolons, and malformed at-rules with line/column positions.

  • CSS to SCSS converter: transforms standard CSS into Sass syntax, converting @media rules to @include, expanding shorthand properties, and handling nested selectors appropriately.

  • Property sorter: alphabetically orders CSS properties within each rule block using the recommended ordering convention (positioning, box model, visual, typography, animation).

  • Vendor autoprefixer: automatically adds -webkit-, -moz-, -ms-, and -o- prefixes to CSS properties that require them for cross-browser compatibility.

  • CSS variables extractor: lists all custom properties (--variable-name) defined in your CSS with their values for easy reference and reuse.

  • Syntax highlighting with color-coded selectors, properties, values, at-rules, comments, and custom properties.

  • CSS statistics: rule count, property count, nesting depth, and output byte size displayed as meta badges.

  • Shareable URLs: gzip-compresses your CSS into a URL parameter so you can share stylesheets with teammates.

  • Works entirely in your browser — no CSS is ever sent to any server. Your stylesheets stay completely private.

  • Keyboard shortcuts for power users: ⌘⇧F to format, ⌘⇧M to minify, ⌘⇧V to validate, ⌘⇧K to clear.

  • Large-input warning with byte count — alerts you when the input may slow down formatting.

  • Auto-format on type: toggle live formatting as you type with the Auto Format checkbox.

Frequently Asked Questions

Is this CSS formatter free?
Yes, DevFlow CSS Formatter is completely free with no usage limits. All formatting, minification, validation, SCSS conversion, property sorting, and autoprefixing runs directly in your browser — no account or signup required.
Is my CSS data safe?
Your CSS is processed entirely in your browser using pure JavaScript. No CSS is ever transmitted to a server or stored anywhere outside your browser. Your stylesheets stay completely private on your machine.
What does CSS formatting do?
CSS formatting (also called beautifying or prettifying) takes compact, minified, or poorly indented CSS and reformats it with consistent indentation, line breaks, and spacing. This makes the stylesheet human-readable and easier to debug, review, and maintain.
What is CSS minification?
CSS minification removes unnecessary whitespace, line breaks, comments, and optional semicolons from CSS to reduce file size. Minified CSS loads faster in browsers and is commonly used for production deployment, embedded stylesheets, or storing CSS in JavaScript strings.
What does property sorting do?
Property sorting alphabetically orders all CSS properties within each rule block. This produces consistent, predictable output that is easier to scan in code reviews and creates smaller diffs when properties change. Some teams also use logical property ordering (positioning first, then box model, etc.).
How does CSS to SCSS conversion work?
The SCSS converter transforms standard CSS into Sass (SCSS) syntax. It converts @media queries appropriately, expands shorthand properties where needed, and handles the syntax differences between CSS and SCSS. The output is valid SCSS that can be used in Sass-powered projects.
What is vendor autoprefixing?
Vendor autoprefixing adds browser-specific prefixes (-webkit-, -moz-, -ms-, -o-) to CSS properties that historically required them for cross-browser compatibility. While modern browsers have largely converged on unprefixed properties, autoprefixing ensures older browsers still render styles correctly.
What CSS validation checks are performed?
The validator checks for: unbalanced braces and brackets, invalid property names or values, missing semicolons, malformed at-rules (@media, @import, etc.), invalid selectors, and duplicate property warnings. Each issue includes its severity and exact location.
How do I extract CSS custom properties?
The Extract Variables action scans your CSS for all custom properties (--variable-name) defined using the :root selector or any other selector. It lists each variable with its name and value, making it easy to see all the design tokens in your stylesheet.
Can I upload a CSS file?
Yes. Click the upload icon in the input panel header to select a .css file from your computer. You can also drag and drop files directly onto the input area. The file contents are loaded for formatting.
Does it work offline?
Yes. All formatting logic is bundled with the page as pure JavaScript. Once the page has loaded, the CSS Formatter works without an internet connection — no network requests are made during formatting.

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