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.
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 and no account.
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 |
What UnMinify does not check before it reformats
CSS Unminifier builds every result from one fixed setting: four-space indentation, hardcoded in the click handler with no dropdown or textbox anywhere on the page to change it. Paste a stylesheet written with two-space or tab indentation and the output still comes back at four spaces every time - there is no way to request a different width.
The input and output panes also run with bracket matching turned off, and UnMinify never parses the pasted text into a syntax tree before calling the beautifier - it reformats whatever bytes sit in the pane. Paste a stylesheet with a missing closing brace or an unbalanced selector and the tool will not underline it, refuse to run, or warn you; it reformats the broken text and hands it back as-is. If a stylesheet is not rendering correctly in the browser, checking it with a CSS validator or your editor's own linter first is the faster way to find the actual syntax error - CSS Unminifier's job starts once the file is already valid CSS and the only problem left is that it is unreadable.
Reformatting also cannot recover what the build step already discarded: class names a minifier has hashed stay hashed, because the original names are not in the bytes you pasted. Whitespace is the only thing the tool puts back.
Pair the unminifier with a text diff online tool
Pair CSS Unminifier with a text diff online tool after the production stylesheet is re-indented: compare the readable copy line by line against the previous revision so selector drift stands out before you edit.
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.
FreetoolOnline Editorial TeamFrequently 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.
Can I unminify more than one CSS file at a time?
No. UnMinify reads the text in the input pane once and writes one result to the viewer pane; there is no batch mode, folder upload, or file queue. Unminify one stylesheet, copy the result, then paste the next file in to repeat the process.
Can I change the indent from four spaces to two spaces or tabs?
No. The four-space indent is fixed in the tool's code, and there is no dropdown or textbox on the page to switch to two-space or tab indentation - every stylesheet comes back at the same four-space width regardless of how it was originally written.
- paste a minified stylesheet into the input pane above and read the beautified result instantly.