The short answer
PostCSS does not stand for a longer phrase. It is not an acronym like HTML (HyperText Markup Language) or CSS (Cascading Style Sheets). The name is built from two parts: post, a prefix meaning “after”, and CSS, the stylesheet language it works on. Together they describe the original idea: a tool that works on CSS after you have written it.
So when someone asks “what does PostCSS stand for?”, the most accurate reply is: it stands for processing CSS with JavaScript plugins, and the name points to the fact that it works on real CSS instead of a custom language that is compiled into CSS.
Why “post” and not “pre”?
When PostCSS appeared in 2013, front-end developers already knew preprocessors such as Sass, Less and Stylus. A preprocessor reads its own syntax, with variables, mixins and functions, and outputs plain CSS. The work happens before CSS exists.
The first big job PostCSS was used for did the opposite. Autoprefixer took finished, standard CSS and added vendor prefixes to it. That is work done after CSS is written, so the community called these tools postprocessors. The name PostCSS followed that logic.
Over time the label stopped fitting. Plugins can now add new syntax, which is preprocessor-style work, as well as optimise finished CSS. The PostCSS team has since described the project simply as a CSS processor.
We explain the pre versus post distinction in more depth in What is the meaning of “post” in CSS?
Where PostCSS came from
PostCSS was created by Andrey Sitnik, a front-end developer at the agency Evil Martians. The project grew out of his earlier tool, Autoprefixer:
- March 2013: Autoprefixer started as a plugin for Rework, another CSS framework of that time. It was first named
rework-vendors. - September 2013: as Autoprefixer grew, Rework could not handle its needs well, so Sitnik began a new parser and plugin system built on the same ideas. That project became PostCSS.
- November 4, 2013: the
postcsspackage was first published to npm. The registry still records this creation date.
Autoprefixer was then rebuilt on top of PostCSS and became its most famous plugin. Today the official README describes PostCSS as a tool for transforming styles with JS plugins, and notes that it is built by Evil Martians.
The alchemy theme: logo and release names
The name is plain, but the branding is playful. The PostCSS logo is described in the official README as the philosopher's stone, the legendary alchemical substance said to transform base metals into gold. That is a neat metaphor: PostCSS takes ordinary CSS and transforms it.
The theme continues in the release names. Major PostCSS versions are given code names taken from the list of spirits in the old grimoire Lemegeton Clavicula Salomonis. For example, PostCSS 8.0, released in September 2020, was called “President Ose”. The names are a tradition, not a technical feature, but they explain why the project's visuals look like an alchemy book.
What “PostCSS” means in practice today
Whatever the history, the practical meaning is clear. When a developer says “we use PostCSS”, they usually mean:
- The project has the
postcsspackage installed from npm. - A config file such as
postcss.config.jslists one or more plugins. - A build tool (Vite, webpack via postcss-loader, the CLI or another runner) passes CSS through those plugins.
| Term | What it means | Relation to PostCSS |
|---|---|---|
| Preprocessor | Compiles a custom syntax into CSS | Plugins like postcss-nested can do similar work |
| Postprocessor | Changes CSS that already exists | The original idea behind the name |
| Processor | Generic term for both | How the PostCSS team describes it now |
| Plugin | A JavaScript function that edits the CSS tree | Where all real transformations happen |
Common misreadings of the name
“Post” as in HTTP POST
PostCSS has nothing to do with the HTTP POST method or with sending CSS to a server. It runs locally during your build.
“Post” as in blog post
It is also not a CMS feature for styling posts. The word is the Latin prefix for “after”.
“PostCSS is the next version of CSS”
No. CSS is a W3C standard. PostCSS is an independent open-source tool that reads and writes standard CSS. Plugins like postcss-preset-env let you use upcoming CSS features early, but PostCSS itself is not a CSS version.
How to write and say it
The official spelling is PostCSS, with a capital P and capital CSS. The npm package name is lowercase, postcss, because npm package names are lowercase. People usually say it as “post C-S-S”.
Summary
- PostCSS is not an acronym; it combines “post” (after) and “CSS”.
- The name comes from the 2013 idea of CSS postprocessors such as Autoprefixer.
- It was created by Andrey Sitnik at Evil Martians and first published to npm on November 4, 2013.
- The project now calls itself a CSS processor because plugins can do both pre- and post-style work.
Next, see how PostCSS works under the hood or check the latest PostCSS version.
Get PostCSS 8.5.32
Free, MIT licensed, downloaded from the official GitHub repository.
