Bootstrap 5 vs Semantic UI — Is Semantic UI Still Relevant in 2026?

Semantic UI had the best class names in the game. ui primary large button. ui three column grid. ui labeled icon menu. Reading Semantic UI HTML was like reading a description of the UI — it made sense in plain English.

That was genuinely clever and it attracted a real following between 2013 and 2018. I used it on a few projects. The components were good, the theming system was flexible and the docs were beautiful.

Then development stalled.

What Happened

Semantic UI was largely a one-person project maintained by Jack Lukic. Around 2017-2018 he moved on to other work and development essentially stopped. The last official release of Semantic UI was 2.4.2 in October 2018.

The community forked it as Fomantic UI and continued development there. Fomantic is more active — it's added components, fixed bugs and worked on reducing the jQuery dependency. But it's still a small community project compared to Bootstrap.

Technical Comparison

Class naming: Semantic UI wins clearly. ui red button vs Bootstrap's btn btn-danger. The semantic approach is more readable, though it requires a slightly different mental model.

Component coverage: Both have extensive component libraries. Semantic UI/Fomantic actually had some components Bootstrap didn't — rating stars, step progressors, sticky elements — before Bootstrap added equivalents.

JavaScript: Semantic UI requires jQuery. This was manageable in 2015, is a real concern today. Bootstrap 5 dropped jQuery entirely. Fomantic UI is working toward jQuery-optional but it's not there yet for all components.

Customisation: Semantic UI's theming system is powerful but complex — it uses a .variables and .overrides file system per component. Bootstrap's Sass variable override approach is simpler for most use cases.

Maintenance: Bootstrap has a team, regular releases and a massive community. Semantic UI is abandoned. Fomantic has a small active team but can't match Bootstrap's pace.

Documentation: Semantic UI's docs were beautiful and comprehensive. They haven't been meaningfully updated since 2018.

The Reality in 2026

Semantic UI shouldn't be chosen for new projects. The jQuery dependency alone rules it out for modern development practices. The stalled maintenance is the bigger issue.

Fomantic UI is a more viable option but it's still small. If you specifically love the semantic class naming convention and are okay with the smaller ecosystem, Fomantic is worth evaluating. But for most teams Bootstrap 5 is the safer, better-supported choice.

What Bootstrap Took from Semantic UI

Interestingly, Bootstrap has borrowed some ideas. Bootstrap 5's utility class names have gotten more readable over time. The component documentation style improved. Some would argue the competition pushed Bootstrap to keep improving its developer experience.

That's the positive legacy of Semantic UI — it showed the industry that framework class names could be more human-readable, and that influenced how others evolved.

But influence isn't a reason to use a stalled framework on a new project. Bootstrap 5 wins this comparison by a wide margin in 2026.