SSL/TLS Certificate Lookup
Check a domain's SSL/TLS certificate — who issued it, when it expires, and whether the chain is trusted
seisho-h.ed.jp
SSL/TLS Certificate
SSL/TLS Certificate for seisho-h.ed.jp
Valid- Issued by (CA)
- Let's Encrypt
- Subject
- www.seisho-h.ed.jp
- Valid from
- Aug 26, 2026
- Valid until
- Nov 24, 2026 (34 days remaining)
- Public key
- RSA 2048-bit
- Serial
- 06202245220F53E1539625FD001974131DC2
- SHA-256 fingerprint
- 57:07:9A:DB:3E:B9:17:98:E3:38:82:69:D4:01:4D:2E:9A:89:6D:0F:61:8C:F4:35:FF:3F:11:5D:21:F1:AB:3C
- Chain
- YR1 → Root YR → ISRG Root X1
Certificate Authority Authorization (CAA)
No CAA policy is published for this domain — any certificate authority may issue for it.
This certificate has been served since Sep 25, 2026.
Never get surprised by seisho-h.ed.jp's certificate expiring
This is today's certificate. Turn on monitoring and we'll watch seisho-h.ed.jp continuously, notifying you the moment anything moves across all three signals:
Uptime
We visit the site from multiple regions worldwide and email you within minutes if it goes down, with a per-region breakdown so a real outage stands out from a regional blip.
DNS changes
We watch NS, MX, CAA, CNAME, TXT and A/AAAA records, and identify the host, network, and ASN behind them, so a real migration or hijack stands out from routine noise.
TLS certificate
We warn you 30, 14, 7, and 1 days before it expires, and flag it if the issuing authority changes or the certificate is unexpectedly replaced.
Free for your first domain: uptime, DNS, and certificate together. No credit card.