Suggest an editImprove this articleRefine the answer for “What is a CSS postprocessor?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**A CSS postprocessor** is a tool that processes CSS that has already been compiled or written, and automatically makes changes to it aimed at compatibility, optimization or automating routine tasks. **Key point:** unlike a preprocessor, which extends the syntax before CSS even exists, a postprocessor works after the code has been written.Shown above the full answer for quick recall.Answer (EN)ImageA CSS postprocessor is a tool that **processes CSS that has already been compiled or written** and automatically makes changes to it aimed at compatibility, optimization or automating routine tasks. Unlike a preprocessor, which extends the syntax *before* CSS even exists, a postprocessor works *after* the code has been written. --- ### **What postprocessors do** Postprocessors solve practical tasks related to production: **1. Autoprefixing for different browsers** Add the needed vendor prefixes so styles work correctly in old and specific browsers. **2. Optimization and minification** Compress the final CSS: remove whitespace and comments, shorten expressions, reducing file size. **3. Working with future CSS standards** Let you use new CSS capabilities before browsers start supporting them, automatically converting them into compatible code. **4. Automating routine operations** For example, sorting properties, grouping media queries, or generating fallback values. --- ### **Examples of popular postprocessors** - **PostCSS**: a plugin platform (autoprefixer, cssnano and others) - **Autoprefixer**: arguably the most widely used plugin, adding prefixes - **cssnano**: minification --- ### **The key difference from preprocessors** | Tool | Works when | Main purpose | |---|---|---| | **Preprocessor** | before CSS | simplifying and extending the syntax | | **Postprocessor** | after CSS | optimization and compatibility | --- **Summary:** a postprocessor is a tool for the final processing of CSS that brings code up to production level: it makes it compact, cross-browser and more reliable.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.