How it compares

semantic-ui is UI as data: a screen is a typed JSON tree, and a renderer interprets it. That one choice is what separates it from its neighbours — so the useful question is what each of them actually sends over the wire.

Framework	What travels
HTMX, Datastar	rendered HTML fragments
Vaadin Flow	component-tree diffs against a stateful server session
Inertia.js	props for a client SPA framework
Adaptive Cards, JSON Forms	UI as JSON — one card, one form
semantic-ui	UI as JSON — a whole application

Because the payload is an abstract model rather than markup, three things follow that no neighbour offers together: the same tree renders as a live SPA, as no-JS server HTML and inside a visual editor; a screen can run with no backend at all; and a new render target is one function per node type.

Against server-driven frameworks

	HTMX	Datastar	Inertia.js	Vaadin Flow	semantic-ui
What ships over the wire	rendered HTML	rendered HTML + signals	JSON props for a SPA framework	component-tree diffs	abstract UI model (typed JSON)
Server holds UI state	no	no	no	yes — a live tree per session	no — stateless responses
Renderer is	the browser	the browser	the SPA framework	locked in	swappable / pluggable
Client-side state	none	signals	SPA-framework store	none (on server)	none you manage
Backend language	any	any	any	Java only	any — or none at all
Type-safe contract	no	no	partial	yes	yes
Visual (WYSIWYG) editor	—	—	—	—	yes, built in

HTMX and Datastar put markup in your controllers. semantic-ui puts a typed tree there: refactorable, diffable, machine-generatable, and compile-time-checkable in Java, Kotlin or Go. The look of every screen lives in one stylesheet.

Inertia.js keeps a React / Vue / Svelte SPA on the client — its build, its dependencies, its upgrades. semantic-ui drops the SPA framework and still renders the same JSON as plain HTML when no JS is loaded.

Vaadin Flow keeps a live component tree per user on the server. A semantic-ui response is stateless — one tree, one request — so it scales like the rest of your backend, in any language.

The same screen, both ways

An HTMX controller assembles markup, so the app's look lives in every fragment that produces it:

<!-- the server returns this -->
<table class="table table-striped">
  <thead><tr><th>SKU</th><th>Name</th></tr></thead>
  <tbody>
    <tr><td>A-1</td><td>Widget</td>
        <td><button hx-delete="/products/p1" hx-target="closest tr"
                    class="btn btn-sm btn-danger">Delete</button></td></tr>
  </tbody>
</table>

A semantic-ui controller states what the screen is. The renderer and one stylesheet decide how it looks — for every table in the app at once:

{ "type": "table", "id": "products",
  "columns": [
    { "type": "column", "id": "c-sku",  "label": "SKU",  "dataKey": "sku"  },
    { "type": "column", "id": "c-name", "label": "Name", "dataKey": "name" }
  ],
  "rows": [ { "type": "row", "id": "p1", "data": { "sku": "A-1", "name": "Widget" } } ],
  "rowActions": [
    { "type": "action", "id": "del", "label": "Delete", "style": "DANGER",
      "confirm": "Delete this product?",
      "onClick": { "behavior": "APPLY_RESPONSE", "method": "DELETE", "url": "/products/{id}" } }
  ] }

No CSS-framework class names in your backend, and the same payload is what the visual editor reads and writes.

Against JSON-described UI

The closest relatives — both describe UI as data. semantic-ui scales the idea up from a single artefact to an application:

	Adaptive Cards	JSON Forms	semantic-ui
Scope	one card	one form (from JSON Schema)	a whole application
Navigation / routing	—	—	yes (UiPage, triggers)
Partial updates	—	—	yes (UiPatch by node id)
Tables, menus, dialogs, trees	limited	—	yes
Server-side HTML rendering	—	—	yes (Handlebars, no JS needed)
Typed builder API	SDKs per platform	—	yes (Java; any language emits the JSON)

Adaptive Cards proved the model: a JSON UI payload with host-specific renderers, designed to live inside someone else's app. semantic-ui carries it to the whole screen — routing, partial updates, full-page rendering.

JSON Forms turns a JSON Schema into a form, and does it well. In semantic-ui a form is one node type among 27, next to tables, menus, dialogs and trees.

Choosing

Pick semantic-ui when you want a typed, language-agnostic UI contract whose renderer you control, at application scope — see what you can build. Pick HTMX or Datastar when hand-writing markup is what your team actually wants.