About CSS Diff Checker
Compare CSS stylesheets, theme files, or compiled output to see which selectors, rules, and property values changed between builds. Full CSS syntax highlighting in both panes.
Frequently Asked Questions
What is a CSS diff tool?
A CSS diff tool compares two stylesheets and highlights every difference — added selectors and declarations in green, removed ones in red. It is the fastest way to audit what changed between a base stylesheet and a modified version.
Can a CSS diff tool detect differences in minified CSS files?
Yes. Paste both minified files and the diff shows the exact character differences. However, minified CSS is hard to read — format both files first using the CSS Formatter tool, then compare. Formatted CSS diffs are far easier to review for rule changes, selector additions, and value updates.
How do I compare CSS output from two versions of a Sass or Less build?
Compile both versions to plain CSS, then paste each output into the diff panels. Changes in the compiled output directly reveal which rules changed, even if the source Sass was heavily restructured. For source-level comparison, diff the .scss or .less files directly.
What is the best way to review CSS changes in a pull request?
Use this tool to compare the old and new compiled CSS side by side. Focus on specificity changes (selector length and type), new z-index or position values that may cause stacking issues, and media query breakpoint changes. For large design systems, also check that variable (--custom-property) definitions remain consistent.
Is my CSS code sent to a server when using this online diff tool?
No. Comparison runs entirely in your browser. No CSS is transmitted anywhere. This is safe for proprietary design system code, internal brand tokens, and any CSS you consider confidential.
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