atcoder.jp

Observed 2026-07-13T00:18:05.510624879+00:00 (12h ago). Every field below was attested with an Ed25519 signature at scan time.

Up right now

Runs onAmazon

Email byGoogle Workspace

Secured byAmazon

Also uses1PasswordGoogle Search ConsoleStripe

push_legacy

Every line above is a signed observation. Check the math at the bottom of the page.

INFRASTRUCTURE MAPwhat atcoder.jp actually stands on - every host below is a signed observation

atcoder.jp

A / AAAA

13.226.209.5713.226.209.11313.226.209.1913.226.209.24

Amazonserves the site

ns-1144.awsdns-15.orgns-1543.awsdns-00.co.ukns-890.awsdns-47.netns-96.awsdns-12.com

awsdns-15.org + awsdns-00.co.uk + moreanswers its DNS

aspmx.l.google.comalt1.aspmx.l.google.comalt2.aspmx.l.google.comaspmx2.googlemail.com+3 more

Google Workspacereceives its email

TLS

atcoder.jp

Amazonissued its certificate

DNS Records

A 4

13.226.209.57
13.226.209.113
13.226.209.19
13.226.209.24

MX 7

10aspmx.l.google.com
20alt1.aspmx.l.google.com
20alt2.aspmx.l.google.com
30aspmx2.googlemail.com
30aspmx3.googlemail.com
30aspmx4.googlemail.com
30aspmx5.googlemail.com

TXT 9

1password-site-verification=H3CJM364F5GI5P3VXH2PYFGCKI
MS=ms90685883
cloudflare_dashboard_sso=f62aac0af9122a7fff211950f317b6df
google-site-verification=IIyyB5yMWakA7SnvZLuqk-eBDlEj647aY0Rq-c80uIg
google-site-verification=iiXXCv8YJjdE0FWPz6zq0ispBt688ytJaOQfOpwuU3A
pardot884953=58ccd91e72a6f94be7450fef89ee32f712f9e18afb5273954e7d09781c220ec1
stripe-verification=e726551d53f6bea6b1a960e876e9fd88c34f32b723a3b2ecb1a91dfc32fa531d
v=spf1 a:atcoder.jp include:_spf.google.com include:aspmx.pardot.com include:amazonses.com ~all
v=DMARC1;p=none;rua=mailto:dmarcreports@atcoder.jp

NS 4

ns-1144.awsdns-15.org
ns-1543.awsdns-00.co.uk
ns-890.awsdns-47.net
ns-96.awsdns-12.com

SOA 1

ns-96.awsdns-12.com awsdns-hostmaster.amazon.com

TLS Certificates (3)

Common Name	Issuer	Expires
`atcoder.jp`	C=US, O=Amazon, CN=Amazon RSA 2048 M01	Fri, 16 Oct 2026 23:59:59 +0000
`Amazon RSA 2048 M01`	C=US, O=Amazon, CN=Amazon Root CA 1	Fri, 23 Aug 2030 22:21:28 +0000
`Amazon Root CA 1`	C=US, ST=Arizona, L=Scottsdale, O=Starfield Technologies, Inc., CN=Starfield Services Root Certificate Authority - G2	Thu, 31 Dec 2037 01:00:00 +0000

Subdomains (0)

None observed.

The proof

Signed at scan time. Check the math yourself. Every line above is part of one signed observation. Re-hash it and check the Ed25519 signature in your own browser; nothing leaves your machine.

Verify this receipt

Put the receipt on your own site. A live badge showing what DomainDrift observes and signs for atcoder.jp. It updates itself. It attests a signed observation - not that the site is safe.

<a href="https://domaindrift.io/t/atcoder.jp">
  <img src="https://domaindrift.io/badge/atcoder.jp.svg"
       width="300" height="64" alt="DomainDrift signed observations for atcoder.jp">
</a>

Ed25519 Receipt

Receipt ID: 49e2be27-6bfb-4f3a-8351-20245440bc42
Output Hash: 3cdc491580439a2a265ed1ecb49e8005c073741ca1fbc6f3715223e31651217d
Signature: ed25519:ce0ae7ed63f39e093a6a3392a6c76b6b17fcbb185e02921dd7f2b406b4c6736101e1085892c9b4f6169ac1fbbf1293f0c751c15e1b42c8311e71be30340bb500
Public Key: ed25519:178c3bd0f57d9d64b83cc4630753381e1a465005a2bbba3d032371f24af0bfd8
Parent: (genesis)
Plane: fast

Verify this in your browser

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