SSL/TLS Certificate Lookup
Check a domain's SSL/TLS certificate — who issued it, when it expires, and whether the chain is trusted
mas-ma.co.jp
SSL/TLS Certificate
SSL/TLS Certificate for mas-ma.co.jp
Valid- Issued by (CA)
- Let's Encrypt
- Subject
- www.mas-ma.co.jp
- Valid from
- Nov 2, 2026
- Valid until
- Jan 31, 2027 (88 days remaining)
- Public key
- RSA 2048-bit
- Serial
- 05205C00CDB253214D175E54E1E8F24BB097
- SHA-256 fingerprint
- 51:EC:EA:C2:B8:4F:B7:31:0C:F1:96:E7:20:E7:FD:D5:93:E8:1A:0E:16:30:0A:AB:39:54:2F:7F:09:E9:6A:26
- 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 Oct 28, 2026.
Never get surprised by mas-ma.co.jp's certificate expiring
This is today's certificate. Turn on monitoring and we'll watch mas-ma.co.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.
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