Website readiness profile · Snapshot 23 October 2026
costco.com
costco.com's public homepage, certificate and DNS checked against 31 practices and compared with 5,718 E-Commerce & Marketplaces sites.
- Readiness index
- 74/100
- Ahead of
- 62%
- Practices observed
- 19/30
- Popularity band
- Top 1K
E-Commerce & Marketplaces median 71
of measured E-Commerce & Marketplaces sites
1 of 31 could not be measured
Chrome UX Report top-sites list
Readiness by lane
Green: costco.com. Thin bar: E-Commerce & Marketplaces peer median.
Enable
62/100
Peers 86
Harden
75/100
Peers 60
Accelerate
88/100
Peers 69
Recover
0/100
Peers 11
Priority fixes for costco.com
Ordered by impact and by how common each practice is among peers.
Priority 1 · Enable
XML sitemap discoverable
Observed: No sitemap was listed in robots.txt or found at /sitemap.xml.
Why it matters: A sitemap helps search engines find new and updated pages, especially on large or frequently updated sites.
What to do: Generate an XML sitemap of canonical URLs, reference it in robots.txt and submit it in Google Search Console.
87% of E-Commerce & Marketplaces peers do this. Limit: Only the standard location was requested, once, at the time of the check.
Guide: XML Sitemap Guide: Include Only URLs You Stand Behind
Priority 2 · Harden
Framing restricted
Observed: The homepage did not send frame-ancestors or X-Frame-Options, so other sites may frame it.
What to do: Send Content-Security-Policy: frame-ancestors 'self' (or a list of trusted origins). X-Frame-Options: SAMEORIGIN covers older browsers.
On Next.js: Add it in next.config.js headers().
70% of E-Commerce & Marketplaces peers do this.
Priority 3 · Accelerate
No render-blocking scripts in <head>
Observed: The homepage <head> loaded 2 external scripts without async or defer.
What to do: Add defer to scripts that need the DOM, async to independent ones such as analytics, or move them to the end of the body.
On Next.js: Use the next/script component with an appropriate loading strategy.
44% of E-Commerce & Marketplaces peers do this.
Guide: Control Third-Party Scripts Before They Control Your Page
Priority 4 · Enable
Structured data present
Observed: The homepage had no JSON-LD structured data.
What to do: Add JSON-LD for your organization and main content types, then test it with Google's Rich Results Test.
70% of E-Commerce & Marketplaces peers do this.
What costco.com already does well
Practices fewer than half of E-Commerce & Marketplaces peers use.
- CAA records limit who can issue certificatesCAA limits issuance to certainly.com, digicert.com.16% of peers
- HSTS kept for at least a yearHSTS with a 365-day max-age covering subdomains.32% of peers
- DMARC policy enforces quarantine or rejectDMARC policy p=reject.39% of peers
What we saw
- Homepage checked
- https://www.costco.com/
- Homepage response
- HTTP 200
- TLS
- TLSv1.3, HTTP/2
- Certificate
- Certainly, 29-day validity, expiring 2026-11-11
- Platform or framework
- Next.js, Adobe Experience Manager
- DNS operators
- Akamai Edge DNS
- HSTS
- max-age 365 days, includeSubDomains
- DMARC policy
- p=reject
- Homepage HTML
- 3,182 KB, gzip
- Images on homepage
- 22 (avif 64, png 24)
Limits: homepage only, one location, one moment. Header checks reflect the homepage response; other pages may differ.
Stack and providers
Seen in the homepage response, certificate and DNS. Provider pages compare how their customers configure the same checks.
All 31 checks
Select a gap for the method and fix. How each check works
Not observed 11
Observed 19
- HTTP requests move to HTTPS
- HSTS kept for at least a year
- TLS 1.3 negotiated
- Certificate has more than 14 days left
- Certificate lifetime of 100 days or less
- CAA records limit who can issue certificates
- DMARC policy enforces quarantine or reject
- Content Security Policy present
- HTTP/2 negotiated
- HTTP/3 advertised
- HTML compressed
- Static files cached for 30 days or more
- Modern image formats in use
- Offscreen images lazy-loaded
- Canonical URL declared
- Meta description written
- Mobile viewport configured
- Page language declared
- At most one redirect to the homepage
Not measured 1
- robots.txt published
Own costco.com?
Re-run the checks after a change, keep a private action plan in a free workspace, or report a mistake.
Live status for this site: Status Is Down: costco.com. This profile covers configuration only.