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Preload and preconnect builder

List the resources your page needs with module, CORS, and as flags, and get correct preload, preconnect, dns-prefetch, and modulepreload tags or a Link header with warnings.

Set a page URL and list resources, or paste hints to audit.

Nothing here fetches your page or any resource. The page URL only resolves relative paths and tells your origin from third parties. The savings figure is an upper bound, three round trips per preconnected origin at the RTT you typed, not a measurement. Browsers drop preconnects that stay unused for about ten seconds, and the preload scanner already finds anything in your HTML, so preloading more than a handful of resources usually costs more than it saves.
Options

More web & auth tools

- HTTP timing probe (/network/http-timing)
- HTTP header parser (/web/headers)
- CSP evaluator & builder (/web/csp)
All web & auth tools (/web)

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Markdown version: https://nutter.tools/web/preload-preconnect-builder.md
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