Preload and Preconnect Checker
Paste your head and catch the resource-hint mistakes that waste bandwidth: double-downloaded fonts, untyped preloads and missing preconnects.
What this tool gives you
Check resource hints
Paste your page head. Analysis runs locally in your browser — nothing is sent anywhere.
preconnect, dns-prefetch and preload are parsed. The checker flags the mistakes that silently slow real pages down.
What this checker looks for
Resource hints tell the browser what to fetch before it discovers it. Wrong hints cost more time than no hints.
preconnect
DNS + TCP + TLS to an origin before the first real request.
crossorigin on fonts
Font preloads without crossorigin download twice — a silent LCP killer.
as attribute
preload requires as so the browser knows the resource type.
Hint budget
More than ~6 preloads compete with real critical requests.
dns-prefetch
Legacy fallback for browsers that ignore preconnect.
Preload vs preconnect
Preconnect the origin, preload only the one above-the-fold asset.
How to fix the hints
Resource hints reward precision. Fix the biggest waste first.
Preconnect origins
Warm the font CDN and API host before the browser discovers them.
Crossorigin on fonts
Every font preload needs crossorigin or the file downloads twice.
Trim the budget
Keep preloads to the LCP asset and the brand font — nothing else.
Which hint to use when
Each hint solves a different delay. Pairing the wrong one with the wrong problem costs time.
| Hint | Fixes | Watch out for |
|---|---|---|
| preconnect | DNS + TCP + TLS to an origin | Use only for 2–3 critical origins |
| dns-prefetch | DNS lookup only | Weak fallback; skip if preconnect is supported |
| preload | Fetches a known asset early | Needs as; fonts need crossorigin |
| modulepreload | Preloads ES modules for import | Only relevant for module scripts |
| fetchpriority | Raises an image's priority | Not a preload — pair with the real request |
Related GEO pages
Speed lives in markup too — check how images and scripts load alongside hints.
Resource Hint FAQs
Why does a font preload without crossorigin download twice?
Browsers fetch preloaded fonts in CORS mode because font files are cross-origin-checked. If your preload link omits crossorigin, the preload is a no-CORS request, the real fetch is a CORS request, and they don't match — so the font downloads again. Always add crossorigin to font preloads.
What is the difference between preconnect and dns-prefetch?
dns-prefetch only resolves the hostname. preconnect resolves DNS, opens the TCP connection and finishes the TLS handshake, so the first real request starts instantly. preconnect is stronger; dns-prefetch is its legacy fallback for old browsers.
How many preload hints should a page have?
Use preload sparingly — the above-the-fold font, the LCP image, maybe critical CSS. Every preload competes for bandwidth with requests the browser already prioritizes, so more than four to six hints usually slows real users down instead of helping them.