Server-side rendering

By default Inertia renders the first page on the client. Server-side rendering (SSR) renders the initial HTML on the server instead — better Time-to-First-Byte and crawlable content — while subsequent navigations keep using the fast JSON path.

Zerotal offers two approaches: the /__ssr endpoint (standard Inertia SSR) and streaming SSR via inertiaStream().

Which should I use?

Endpoint SSR (ssr: true) — the standard Inertia SSR contract. Turn it on globally and the Inertia client renders the first page through POST /__ssr. Use this when you want crawlable, server-rendered HTML across the whole app with no per-controller change.
Streaming SSR (inertiaStream()) — swap inertia() for inertiaStream() in the controllers whose initial document you want streamed for the fastest TTFB. Use it selectively on heavy landing pages; everything else stays on inertia().

Endpoint SSR

Enable the SSR endpoint in config:

// config/inertia.ts
import { InertiaConfig } from "@zerotal/inertia";
import { env } from "zerotal";

export default InertiaConfig({
  htmlTemplate: "./resources/app.html",
  version: env("ASSET_VERSION", "1"),
  ssr: true, // registers POST /__ssr — requires a server renderer
});

When ssr: true, InertiaProvider registers POST /__ssr, which accepts { component, props, url } and returns { body, head } — the same contract as the Inertia Node SSR server. On a first-page load the server renders the component into the template instead of shipping an empty root <div>; subsequent navigations use the normal JSON path. Pages render with the framework they're authored in: React .tsx via react-dom/server, or Vue .vue via @inertiajs/vue3 + vue/server-renderer — install the server renderer for the framework(s) your app uses.

Streaming SSR

inertiaStream() is a drop-in async alternative to inertia() that uses React 18's renderToReadableStream to improve TTFB. Instead of buffering the whole render, it streams the React output between the template's HTML prefix and suffix:

│ HTML prefix (everything before <!-- @inertia -->) │ → browser starts parsing <head>
│ React component stream                             │ → above-the-fold content arrives early
│ <div> close + page JSON + HTML suffix              │

Swap inertia() → inertiaStream() and await it — nothing else changes:

// app/controllers/PostController.ts
import { inertiaStream } from "@zerotal/inertia";

export class PostController {
  async show(ctx: HttpContext): Promise<void> {
    const post = await Post.findOrFail(ctx.params["id"]);
    return inertiaStream("Posts/Show", { post });
  }
}

Requirements

react-dom/server ≥ 18 (for renderToReadableStream)
The HTML template must contain 
The page component must exist under your pages directory (resources/js/pages/<component>.tsx)

It throws if the template hasn't loaded, or if the component name contains path traversal (.. or a leading /).

inertia vs. inertiaStream

Criterion	`inertia()`	`inertiaStream()`
Return type	`Promise<void>`	`Promise<void>`
Rendering	Buffered HTML string	Streaming `renderToReadableStream`
Response body	Fully buffered string	Streaming `ReadableStream`
TTFB	After full render	After the prefix is flushed
XHR navigation	JSON (the normal path)	N/A — only the first-page document

For XHR navigations (X-Inertia: true), keep using inertia() — streaming only benefits the initial HTML document load.

Tip — Stream the heaviest landing pages and leave everything else on inertia().

Next steps

Inertia overview — the guide's front page and the rest of the sections.
Reference — the full API surface in one table.