When to use this CSS unminifier
Use this CSS unminifier (beautifier) online when you have a one-line, production-built stylesheet and you need to read or edit it. Paste the minified CSS into the input pane, click UnMinify, and the tool returns the same rules with proper indentation, line breaks, and readable formatting so each selector and declaration sits on its own line. Pair this tool with the CSS Minifier above when you want to inspect a third-party stylesheet, debug a specificity bug, or hand off a clean copy to a teammate. Free, in-browser, and no account required.
Unminify CSS Instantly for Easier Debugging
Paste a one-line, production-built stylesheet into the input pane and click UnMinify. The packed rules expand into four-space indentation with one selector per line, so the file is readable again for debugging or editing.
Whether you are chasing a specificity bug, reading a third-party stylesheet, or handing a teammate a clean copy, the re-indented output gives you the clarity to review, edit, and ship the fix.
Key features
- Side-by-side viewer with line numbers. The beautified result renders in a viewer pane with line numbers beside the original, and a one-click Copy button puts the clean bytes on the clipboard - so you read the same rule once instead of scrolling between two windows.
- Panes that fit your screen. The editor and viewer auto-resize to your window with a 480 px floor, so a long stylesheet stays scrollable on a laptop and a short one does not collapse into a strip on a phone.
- Stays in your browser. The cssbeautify library loads from the site CDN on first paint, then every UnMinify click is a local re-format with no round-trip to a server, no account, and no copy of the stylesheet kept off your device.
Minified vs unminified CSS at a glance
| Minified CSS | Unminified CSS | |
|---|---|---|
| Layout | One line, whitespace stripped | Four-space indent, one selector per line |
| File size | Smaller - lighter to download | Larger - readable spacing added |
| Best for | Shipping to production | Reading, debugging, and editing |
Keep the minified copy for production and beautify a copy here whenever you need to read or change it. The tool reformats whitespace only - it does not lint, fix broken declarations, or recover class names a build step has hashed.
Pair the unminifier with a text diff online tool
Once the production stylesheet is re-indented with four-space blocks and one selector per line, the next step in a debug pass is usually a line-by-line compare against the previous build or the source-of-truth in the repository. The site's Text Diff tool on the Developer Tools hub reads two pasted blocks of text side by side and highlights added, removed, and changed lines, so a developer chasing a specificity regression or a selector-rename drift can copy the beautified output here, paste both revisions into the Text Diff pane, and read the exact rule that moved. Both tools run in the same browser tab with nothing uploaded.
Wondering whether to use this CSS Unminifier or a source formatter like Prettier? CSS Unminifier vs Prettier: when to use each covers the read-shipped-CSS vs format-source-CSS split in 30 seconds, plus what neither tool can recover after a tree-shaken build.
This unminifier is the inverse of the CSS minifier: compress a stylesheet for production there, then beautify a shipped one for debugging here. When the file in front of you is a packed script rather than a stylesheet, the JavaScript unminifier runs the same re-indent for JS, and the full format and hash set lives on the developer tools hub.
Frequently Asked Questions
How does it work?
The unminifier loads the cssbeautify library from the site's CDN on first paint, then runs every UnMinify click locally against the textarea content with a four-space indent, returning the same rules with clear indentation and spacing for easy review and modification.
Is my CSS uploaded to a server?
No. The conversion runs entirely in your browser tab. There is no round-trip to a server, no account, and no copy of the stylesheet retained anywhere off your device.
Does unminified CSS affect website performance?
No, unminified CSS is generally used for development or debugging. In production, minified CSS should still be used for optimal performance.
- paste a minified stylesheet into the input pane above and read the beautified result instantly.