SSL/TLS Certificate Lookup
Check a domain's SSL/TLS certificate — who issued it, when it expires, and whether the chain is trusted
open-t.nl
SSL/TLS Certificate
SSL/TLS Certificate for open-t.nl
Valid- Issued by (CA)
- Sectigo Limited
- Subject
- *.open-t.nl
- Valid from
- Feb 27, 2026
- Valid until
- Mar 24, 2027 (136 days remaining)
- Public key
- RSA 2048-bit
- Serial
- B81D62246B1F59A62F90EEA3C78DEA17
- SHA-256 fingerprint
- 98:40:A2:71:98:88:1F:A8:74:C3:C7:76:1F:87:A0:86:1B:69:E4:C3:39:7A:C9:2D:E3:45:61:4D:CF:97:7B:88
- Chain
- Sectigo Public Server Authentication CA DV R36 → Sectigo Public Server Authentication Root R46 → USERTrust RSA Certification Authority
Certificate Authority Authorization (CAA)
The serving CA (Sectigo Limited) is authorized by this domain's CAA records (letsencrypt.org, sectigo.com).
Never get surprised by open-t.nl's certificate expiring
This is today's certificate. Turn on monitoring and we'll watch open-t.nl 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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