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 osbos.pl
Expired- Issued by (CA)
- Let's Encrypt
- Subject
- osbos.pl
- Valid from
- Aug 20, 2025
- Valid until
- Nov 18, 2025 (expired 269 days ago)
- Public key
- RSA 4096-bit
- Serial
- 052E7BC7C7F0D986A9626EA5E0988A1DB59C
- SHA-256 fingerprint
- 85:C4:D6:75:D5:71:85:01:D6:8E:72:4F:28:4A:3A:AD:EB:66:3B:3E:B3:3C:71:B9:BD:82:4F:54:8E:D7:92:D7
- Chain
- R13 → ISRG Root X1
Certificate Authority Authorization (CAA)
No CAA policy is published for this domain — any certificate authority may issue for it.
Never get surprised by osbos.pl's certificate expiring
This is today's certificate. Turn on monitoring and we'll watch osbos.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.
Free for your first domain: uptime, DNS, and certificate together. No credit card.