SSL/TLS Certificate Lookup

Check a domain's SSL/TLS certificate — who issued it, when it expires, and whether the chain is trusted

SSL/TLS Certificate for sejnet.pl

Valid
Issued by (CA)
Let's Encrypt
Subject
sejnet.pl
Valid from
Jul 4, 2026
Valid until
Oct 2, 2026 (62 days remaining)
Public key
RSA 2048-bit
Serial
05D555B7C555075EA5F8A5335E1A80F113DB
SHA-256 fingerprint
4D:E9:28:7E:1A:D2:F0:7A:E2:E5:2F:7E:69:3B:FB:D8:91:E0:8B:8A:0E:DE:B8:C7:F2:6C:CA:66:BF:1D:6A:DD
Chain
YR2 → Root YR → ISRG Root X1
Subject Alternative Names (2)
boa.sejnet.pl, sejnet.pl

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 Aug 1, 2026.

Never get surprised by sejnet.pl's certificate expiring

This is today's certificate. Turn on monitoring and we'll watch sejnet.pl 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, DNSSEC, CNAME 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.

Monitor this certificate free

Free for your first domain: uptime, DNS, and certificate together. No credit card.