Semantic UI installs with a gulp task, and its last release is 2.5.0

npm install runs a gulp task, and the plugins are peer dependencies

The recommended install is one line, and the line hides the work:

npm install semantic-ui  # Use themes, import build/watch tasks into your own gulpfile.

package.json sets the install script to `gulp install`, so npm invokes gulp while installing rather than unpacking a stylesheet. Everything that task needs sits in peerDependencies with the version written as `*`: gulp, gulp-less, gulp-rtlcss, gulp-concat-css, gulp-clean-css, gulp-uglify, gulp-autoprefixer, gulp-copy, gulp-flatten, map-stream, yamljs and the rest, 27 entries in total.

Two consequences follow. A project that has never used gulp has to satisfy the whole peer set before the install can finish, and a failure during npm install is a failing gulp task rather than a missing file. The `*` ranges mean the host project supplies whatever versions resolve, so a newer major of one plugin is not something the package will hold you back from. The comment in the install line is the other half of the deal: themes and the build and watch tasks are meant to be imported into your own gulpfile, so you are adopting a build integration, not just a dependency.

Three levels of variable inheritance, 3000+ variables, and EM for sizing

The theming model is the reason to look at this framework. It carries 3000 or more CSS variables, organised across three levels of variable inheritance, a structure the README compares to SublimeText. A theme is therefore a set of overrides on those variables rather than a copy of the stylesheets, and the level you override at decides how far the change reaches.

That reach is the trade. Because the levels inherit into each other, a value set at the top level moves everything below it, including components you did not touch, and a value set lower down can be overridden by anything above. Sizing is built with EM values for responsive design, which ties component size to the root font size, so a change to base typography scales controls that never mentioned a breakpoint. Flexbox friendliness is listed alongside those, and the grid depends on it.

Direction is handled the same generated way. An RTL version is produced by the build tools by selecting `rtl` from the install script, so right-to-left support is a build target you choose rather than a stylesheet you import. Pick the variable level deliberately, and check what inherits from it before you change it.

Pull requests land on next, and 2.5.0 is the newest published version

Maintenance state comes down to two dates. The default branch is master and the last push is dated 2024-11-27, while the newest release is 2.5.0, published 2022-10-06. Before it sit 2.4.1 from 2018-10-13 and 2.4.0 from 2018-09-17, so the version history has one release in 2022 and then a long gap back to 2018. The repository is not archived.

What 2.5.0 bought was compatibility: Semantic UI is now compatible with Node 18 and Gulp 4. That is a two-year-old answer to the Gulp 4 migration, and it tells you the gulp toolchain this release was tested against rather than what a current one does.

The branch layout compounds the gap. Contributors are asked to merge into the next branch, and the README ties that branch to demonstrating a fix in the next release, so fixes land somewhere other than master and ahead of whatever version npm serves. If you are on 2.5.0 today, work merged to next is work you do not have, and the README does not give a date or a schedule for the release that would carry it.

Only bugs with a JSFiddle test case get triaged

The support policy is unusually specific about what counts as a report. Usage questions are asked to go to the Gitter chatroom or StackOverflow rather than GitHub Issues, and GitHub Issues is reserved for enhancements and bugs. For a bug, the requirement is a link to a test case plus steps to reproduce, and the README is explicit that only bugs which include a test case can be triaged.

The test case is a forkable JSFiddle at a fixed address that the project keeps pointing at. The README also allows a documentation page that is plainly wrong to stand in as a test case, provided the reproduction is spelled out.

What this means in practice is that the diagnosis work moves to the reporter. If your bug depends on a build config, a gulpfile of your own or a server-side dependency, a JSFiddle is a poor reproduction vehicle, and a report built that way arrives without the case the triage rule asks for. Budget for building an isolated repro before you file, and expect no other route in.

Six install scripts, and each one drops something

The full package is one option among several, and the differences are about what reaches your build. `npm install semantic-ui` brings themes plus the build and watch tasks. `npm install semantic-ui-css` is the CSS-only route with no build tool involved. `npm install semantic-ui-less` gives you the LESS sources, and `less-plugin-semantic-ui` is the LESS plugin, which lives in a separate repository rather than this one. For other stacks there is `ember install:addon semantic-ui-ember`, `meteor add semantic:ui`, `meteor add semantic:ui-css`, and `bower install semantic-ui`.

The choice inside the family is a build toolchain against a prebuilt stylesheet. Semantic UI itself wants gulp on the host, and the LESS plugin wants a different repository's release rhythm on top of that. The CSS-only route is the cheapest to install and the one that gives up the variable-level theming and the rtl build step, because those come out of the build rather than the stylesheet.

An interactive installer is part of the package too, for setting up a project. The integration wiki is named as the place for further options beyond this list.

The support matrix ends at IE 11, and IE 9 loses the grid

Browser support is stated as a floor rather than a tested range: the last two versions of Firefox, Chrome and Safari on Mac, IE 11 and up, Android 4.4 and up, Chrome for Android 44 and up, iOS Safari 7 and up, and Microsoft Edge 12 and up.

The IE 9 note is the one with consequences. Some components work in IE 9, but grids and the other flexbox components are not supported there and may not appear correctly. A layout that fails to lay out in an old browser is a very different debugging session from a component that throws, and the failure mode is visual.

Two things the matrix does not tell you. It does not say which versions were tested on a given date, so a floor of IE 11 and iOS Safari 7 tells you nothing about a browser release that has not shipped yet. And the repository carries its own browser list configuration in a .browserlistrc at the root, which is a separate piece of state from the support table in the README, so the two can disagree without either being wrong. Check the file your build actually reads.

SCSS has no supported route to these variables, and no competitor is named

The project names partners rather than rivals. React, Angular, Meteor and Ember are listed as frameworks it integrates with, an integration wiki covers the rest, and the repository's examples directory holds working pages for a grid, a login form, a responsive layout, a sticky element, a fixed element, an attached element, a components gallery and theming. Bootstrap appears in that examples directory as a page, not as a comparison.

The open gap is SCSS. The places-to-help table states that SASS needs a pull request to support variables inside @import, and links that change to the sass repository. Until it lands, a Sass-based pipeline cannot import Semantic's variables the way a LESS pipeline can, which pushes those users toward the separate LESS plugin repository or toward the prebuilt CSS.

So the honest comparison for a reader choosing today is between this framework with a gulp and LESS toolchain you maintain, and a prebuilt stylesheet with no theming pipeline, rather than between Semantic and another component library on features. The README makes no performance claim, no bundle-size claim and no comparison with any other framework, so nothing here should be read as a verdict on alternatives.

Editorial conclusion

Adopt Semantic UI if you want a large element set with theming done through variable overrides rather than a stylesheet fork, and you are willing to own a gulp toolchain. Do not adopt it for a greenfield React or SCSS project: the repository names React as a partner framework but ships no React install of its own, and the SCSS path waits on a change to how SASS handles variables inside @import. Before you commit, check two things. Look at the last commit on master, 2024-11-27, against the newest release, 2.5.0 from 2022-10-06, and accept that fixes merged into the next branch are not in the published package. And count the peer dependencies before you install, because `gulp install` runs during npm install and the package expects the host project to supply 27 of them at unpinned versions.

Frequently asked questions

Official sources

1. Official documentation
2. Official README
3. Project repository
4. Release notes