CSS Formatter — Beautify and Indent CSS Stylesheets Online

CSS does not need to be minified to work, but minified CSS is painful to read, hard to debug, and awkward to share. When you receive a stylesheet from a build tool, copy rules from a third-party widget, or write CSS without automatic formatting in your editor, the result can be a dense block of selectors and declarations with no visible structure. A CSS formatter restores that structure in a single step, using the indentation width you prefer.

This tool runs entirely in your browser. The CSS you paste or upload never leaves your device. Pick an indent size, format, and optionally download or copy the result. No signup, no server, and no logging.

Why format CSS

Readable stylesheets are easier to maintain, whether you are reviewing your own work or inspecting code written by someone else. Formatting CSS helps you:

• Spot selector structure. When rules are indented consistently, nested media queries, pseudo-classes, and grouped selectors are easier to follow.
• Review minified output. Build tools, email platforms, and inline style generators often produce minified CSS. Formatting makes those stylesheets reviewable without digging through a single long line.
• Share snippets safely. Copy-pasted CSS in tickets, documentation, or chat is far easier to read when each declaration sits on its own line.
• Edit and reformat. Because formatting happens in place, you can tweak a rule and run the formatter again to keep the result tidy.

A CSS formatter does not validate your stylesheet. It does not check whether properties exist, whether values are valid, or whether selectors are correct. It only adjusts whitespace so the hierarchy is visible and the file is easier to work with.

How to use

Paste or type CSS

Open the CSS source textarea and paste your stylesheet directly. Multi-line input works the same way as a short rule set. As you type, line numbers on the left update automatically so you can refer to specific lines when discussing a rule.

Set the indent size

The Indent size field controls how many spaces each nesting level uses. The default is 2, which matches many common style conventions. You can raise it to 4 or 8 for deeper visual separation, or lower it to 1 for a more compact look. The field accepts values from 1 to 8.

Format CSS

Click Format CSS to beautify the content of the textarea. The formatter adds line breaks between rules, indents declarations inside each rule, and aligns nested blocks so the structure is easy to scan. If the textarea is empty, you will see a friendly prompt asking you to paste or upload CSS first.

Upload a file

Use Upload file to open a .css file from your computer. The file is read with the browser's FileReader API and placed into the editor. No file is uploaded to any server. Files larger than 1 MB are rejected with a message asking you to use a smaller file.

Download the result

After formatting, click Download CSS to save the current content as formatted.css. The file is generated from a Blob and downloaded through a temporary object URL, the same way a browser would handle a "Save As" action.

Copy the formatted output

Click Copy CSS to write the editor content to your clipboard. A short confirmation appears so you know the copy succeeded. If the clipboard API is unavailable, the button fails silently and the content stays in the editor for manual selection.

Clear the editor

Click Clear editor to empty the textarea. This is useful when you want to start over with a fresh rule set without reloading the page.

Example

Here is a typical before-and-after. The input is a compact, minified rule set. After formatting with an indent size of 2, the same rules become readable.

Before — compact:

body{margin:0;font-family:system-ui,sans-serif;color:#111;background:#fff}h1{font-size:2rem;margin-bottom:1rem}a{color:#0066cc;text-decoration:none}a:hover{text-decoration:underline}@media(min-width:768px){.container{max-width:720px;margin:0 auto;padding:0 1rem}}

After — formatted (indent size 2):

body {
  margin: 0;
  font-family: system-ui, sans-serif;
  color: #111;
  background: #fff;
}

h1 {
  font-size: 2rem;
  margin-bottom: 1rem;
}

a {
  color: #0066cc;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

@media (min-width: 768px) {
  .container {
    max-width: 720px;
    margin: 0 auto;
    padding: 0 1rem;
  }
}

Notice how each rule now starts on its own line, declarations are indented inside the selector, and the media query block is visually distinct. If the original stylesheet had an issue, such as a missing semicolon or a misplaced brace, the inconsistent indentation after formatting makes that easier to spot.

Tips for cleaner output

• Paste the whole stylesheet when possible. Formatting a fragment works, but the clearest output comes from a complete rule set that includes selectors, media queries, and any grouped rules.
• Review selector grouping. The formatter preserves the grouping you wrote. If several selectors share a rule in your source, that grouping stays intact after formatting.
• Use a larger indent for deeply nested media queries. Complex responsive stylesheets can nest many conditions. An indent size of 4 or 8 can make those trees easier to read.
• Format, edit, format again. Because the formatted output replaces the textarea content, you can make a small change and re-run the formatter to keep the result tidy.

FAQ

Does the formatter upload my CSS to a server?

No. The entire process runs in your browser using client-side JavaScript. Files are read with FileReader and output is generated from a local Blob. Nothing leaves your device.

What if my CSS is invalid or has syntax errors?

The formatter will still attempt to produce indented output from whatever you paste. It does not validate your stylesheet. If the input is malformed, the result may not be ideal, but the tool will not crash. If something goes wrong during formatting, a friendly message appears instead of an empty screen.

Can I format fragments, or only full stylesheets?

Both. Paste a single rule, a group of selectors, or an entire file. The formatter indents based on blocks and declarations, so it works with any CSS-like input.

How large can the input be?

There is no hard limit for paste input, but the editor is designed for everyday stylesheets. File uploads are capped at 1 MB. If you need to format something larger, consider splitting it into smaller pieces.

Does the formatter change my code in other ways?

No. It only adjusts whitespace: indentation, line breaks, and the placement of braces and declarations. It does not rename properties, reorder rules, or strip comments.

Can I use tabs instead of spaces?

The indent size field controls the number of spaces per level. If you prefer tabs, you can set the indent size to 1 and convert spaces to tabs in your own editor after copying the result. The formatter itself uses spaces.

Related tools

• HTML Formatter — beautify and indent HTML markup with the same browser-side approach.