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 gmx.de
Valid- Issued by (CA)
- Deutsche Telekom Security GmbH
- Subject
- *.gmx.de
- Valid from
- Mar 11, 2026
- Valid until
- Sep 24, 2026 (60 days remaining)
- Public key
- RSA 3072-bit
- Serial
- 20A1EB7F87FB398D48BE330B89AABB99
- SHA-256 fingerprint
- FD:34:8E:48:19:E0:06:25:E5:AF:1F:74:A5:15:36:7C:E3:12:44:AA:97:47:12:86:3F:60:58:44:B5:0E:92:49
- Chain
- Telekom Security ServerID OV Class 2 CA → T-TeleSec GlobalRoot Class 2
Certificate Authority Authorization (CAA)
CAA restricts issuance to digicert.com, sectigo.com, telesec.de; we couldn't map the serving CA (Deutsche Telekom Security GmbH) to one of these identifiers.
This certificate has been served since Jul 20, 2026.
Never get surprised by gmx.de's certificate expiring
This is today's certificate. Turn on monitoring and we'll watch gmx.de 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.
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