seo/ssr-disabled · SSR disabled

export const ssr = false makes a route's content invisible to non-JS crawlers and slower to first paint.

Severity: warning · Category: seo

What it checks

Flags SvelteKit route files that disable server-side rendering with export const ssr = false (the satisfies/as and same-file alias-export forms included). Disabling it in the root +layout turns the whole app into an SPA, and gets a stronger, app-wide message.

Not flagged: csr = false (server-only rendering, which is fine for SEO), non-literal values like export const ssr = dev (not statically evaluable), and non-exported const ssr = false (has no effect in SvelteKit).

Why it matters

SvelteKit’s own SEO guidance: server-side rendered content is indexed more frequently and reliably, so leave SSR on unless you have a good reason not to. On top of the indexing risk, SPA mode ships an empty page that must fetch and run JavaScript before anything renders, adding a network round trip before first paint.

Note that prerender = true does not neutralise this: with ssr = false the prerendered output is still an empty shell.

How to fix

Scope ssr = false to routes that genuinely don’t need SEO:

export const ssr = false; // fine — suppress or turn the rule off if this is deliberate

For a deliberate full SPA, disable the rule in your config:

export default {
  rules: {
    'seo/ssr-disabled': 'off'
  }
};

or add // svelte-vitals-disable-next-line seo/ssr-disabled above the declaration.

Mode differences

None. This rule reads source, the same .svelte and .ts files, everywhere it runs. The CLI, the Vite plugin’s build pass, and the live dashboard’s static baseline all report it identically, and the rendered-HTML pass never re-evaluates it. Scoping a run with --route skips it: component-scoped rules have no route to attribute a finding to.

Disabling

Silence a single occurrence with  on the line above it, or turn the rule off:

export default {
  rules: {
    'seo/ssr-disabled': 'off'
  }
};