Website readiness profile · Snapshot 23 October 2026
costco.co.uk
costco.co.uk's public homepage, certificate and DNS checked against 31 practices and compared with 5,718 E-Commerce & Marketplaces sites.
- Readiness index
- 72/100
- Ahead of
- 54%
- Practices observed
- 20/31
- Popularity band
- Top 50K
E-Commerce & Marketplaces median 71
of measured E-Commerce & Marketplaces sites
0 of 31 could not be measured
Chrome UX Report top-sites list
Readiness by lane
Green: costco.co.uk. Thin bar: E-Commerce & Marketplaces peer median.
Enable
51/100
Peers 86
Harden
75/100
Peers 60
Accelerate
85/100
Peers 69
Recover
100/100
Peers 11
Priority fixes for costco.co.uk
Ordered by impact and by how common each practice is among peers.
Priority 1 · Enable
robots.txt published
Observed: No robots.txt file was returned at the site root.
Why it matters: robots.txt is where crawlers look first for crawl rules and sitemap locations. Without it, they assume everything is open.
What to do: Publish /robots.txt with any crawl rules you need and a Sitemap: line pointing to your XML sitemap.
95% of E-Commerce & Marketplaces peers do this. Limit: Only the standard location was requested, once, at the time of the check.
Guide: Robots.txt Guide: Control Crawling Without Hiding Mistakes
Priority 2 · Enable
XML sitemap discoverable
Observed: No sitemap was listed in robots.txt or found at /sitemap.xml.
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.
Guide: XML Sitemap Guide: Include Only URLs You Stand Behind
Priority 3 · Accelerate
Static files cached for 30 days or more
Observed: A same-site stylesheet or script was cacheable for 7 hours, short of the 30-day benchmark.
What to do: Give versioned (fingerprinted) CSS, JavaScript, fonts and images Cache-Control: public, max-age=31536000, immutable, and change the file name whenever the content changes.
60% of E-Commerce & Marketplaces peers do this.
Priority 4 · Enable
Meta description written
Observed: The homepage had no meta description.
What to do: Write a short, specific description of the page for people, not a list of keywords.
95% of E-Commerce & Marketplaces peers do this.
Guide: Meta Titles and Descriptions That Match Search Intent
What costco.co.uk already does well
Practices fewer than half of E-Commerce & Marketplaces peers use.
- Nameservers spread across providersNameservers spread across more than one operator.11% 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.co.uk/
- Homepage response
- HTTP 200
- TLS
- TLSv1.3, HTTP/2
- Certificate
- Certainly, 29-day validity, expiring 2026-11-20
- Platform or framework
- Angular
- DNS operators
- Akamai Edge DNS, plus 1 self-run or other nameserver domain
- HSTS
- max-age 365 days, includeSubDomains, preload
- DMARC policy
- p=reject
- Homepage HTML
- 1,579 KB, gzip
- Images on homepage
- 188 (jpg 198, webp 94, png 19, gif 4, avif 3)
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 20
- 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
- DMARC policy enforces quarantine or reject
- Framing restricted
- Content Security Policy present
- HTTP/2 negotiated
- HTTP/3 advertised
- HTML compressed
- Modern image formats in use
- Offscreen images lazy-loaded
- No render-blocking scripts in <head>
- Canonical URL declared
- Mobile viewport configured
- Structured data present
- Page language declared
- At most one redirect to the homepage
- Nameservers spread across providers
Own costco.co.uk?
Re-run the checks after a change, or verify the site in a free workspace to save reports with history, compare against similar sites and competitors, and track a private action plan. What owners get.
Live status for this site: Status Is Down: costco.co.uk. This profile covers configuration only.