Website readiness profile · Snapshot 23 October 2026

sej.co.jp

sej.co.jp's public homepage, certificate and DNS checked against 31 practices and compared with 5,718 E-Commerce & Marketplaces sites.

Readiness index: 56/100
Ahead of: 13%
Practices observed: 14/31
Popularity band: Top 10K

Measured 2026-10-23 12:00:58 UTC from one location. How we measure

Readiness by lane

Green: sej.co.jp. Thin bar: E-Commerce & Marketplaces peer median.

Enable

64/100

Peers 86

Harden

49/100

Peers 60

Accelerate

63/100

Peers 69

Recover

0/100

Peers 11

Priority fixes for sej.co.jp

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 · Accelerate
Static files cached for 30 days or more
Observed: A same-site stylesheet or script was cacheable for no max-age, 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.
Guide: Browser Caching Guide for Website Owners
Priority 3 · Enable
Canonical URL declared
Observed: The homepage did not declare a canonical URL.
What to do: Add a self-referencing canonical link to every indexable page, using the final https:// URL.
85% of E-Commerce & Marketplaces peers do this.
Guide: Canonical Tags: A Decision Guide for Duplicate URLs
Priority 4 · Harden
DMARC policy enforces quarantine or reject
Observed: The DMARC policy for sej.co.jp was p=none, which asks receivers to take no action on failing mail.
What to do: Publish DMARC with p=none and a reporting address first, fix any legitimate senders that fail SPF or DKIM alignment, then move to quarantine and finally reject.
39% of E-Commerce & Marketplaces peers do this.
Guide: A Practical Website Health Check for Owners

What sej.co.jp already does well

Practices fewer than half of E-Commerce & Marketplaces peers use.

HSTS kept for at least a yearHSTS with a 365-day max-age.32% of peers
Modern image formats in useWebP or AVIF images detected.47% of peers

What we saw

Homepage checked: https://www.sej.co.jp/
Homepage response: HTTP 200
TLS: TLSv1.3, HTTP/2
Certificate: Cybertrust Japan Co., Ltd., 387-day validity, expiring 2027-01-31
CDN or edge: Imperva
DNS operators: 1 self-run or other nameserver domain
HSTS: max-age 365 days
DMARC policy: p=none
Homepage HTML: 120 KB, gzip
Images on homepage: 93 (png 53, jpg 41, webp 19)

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.

Imperva (cdn and edge platform)Cybertrust Japan Co., Ltd. (certificate authority)

All 31 checks

Select a gap for the method and fix. How each check works

Not observed 17

Observed 14

HTTP requests move to HTTPS
HSTS kept for at least a year
TLS 1.3 negotiated
Certificate has more than 14 days left
HTTP/2 negotiated
HTML compressed
Modern image formats in use
Offscreen images lazy-loaded
XML sitemap discoverable
Meta description written
Mobile viewport configured
Structured data present
Page language declared
At most one redirect to the homepage

Own sej.co.jp?

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Live status for this site: Status Is Down: sej.co.jp. This profile covers configuration only.

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