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THE CERTIFICATE BEHIND THE CONNECTION

TLS certificate checker.

Inspect SSL/TLS certificates for any public domain or subdomain.

Checks HTTPS on port 443, including subject alternative names, validity dates and the presented chain.

SSL certificate

TLSv1.3

jon.cz · 188.75.128.90:443

Verified

Certificate chain, hostname and dates verified using this server’s CA store.

Subject
CN=jon.cz
Issuer
C=US O=Let's Encrypt CN=YR2
Valid from
2026-08-29T00:08:28+00:00
Expires
2026-11-27T00:08:27+00:00
Days remaining
50
Serial (hex)
06F40D9A76CD158D862809EC6FD49AEF9BFC
Signature
RSA-SHA256
Public key
RSA 4096

Subject alternative names (SAN)

DNS:jon.cz, DNS:www.jon.cz

SHA-256 fingerprint

FF:89:8F:3A:4F:5E:22:C2:24:F1:57:72:40:E7:26:7F:4D:98:12:61:D4:34:75:A7:0F:C9:1A:38:31:CD:C1:3E
Certificate extensions & PEM
keyUsage
Digital Signature, Key Encipherment
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:FALSE
subjectKeyIdentifier
2D:03:AB:1A:33:F7:BA:50:81:79:60:8A:2F:A4:25:82:50:EC:EB:B9
authorityKeyIdentifier
40:15:2D:26:79:ED:32:20:9E:DF:9A:72:1D:D6:32:1F:81:0C:81:0C
authorityInfoAccess
CA Issuers - URI:http://yr2.i.lencr.org/
subjectAltName
DNS:jon.cz, DNS:www.jon.cz
certificatePolicies
Policy: 2.23.140.1.2.1
crlDistributionPoints
Full Name: URI:http://yr2.c.lencr.org/125.crl
ct_precert_scts
Signed Certificate Timestamp: Version : v1 (0x0) Log ID : C2:31:7E:57:45:19:A3:45:EE:7F:38:DE:B2:90:41:EB: C7:C2:21:5A:22:BF:7F:D5:B5:AD:76:9A:D9:0E:52:CD Timestamp : Aug 29 01:06:59.149 2026 GMT Extensions: none Signature : ecdsa-with-SHA256 30:46:02:21:00:8B:09:82:28:2B:F2:B3:B7:EE:60:5B: 3F:69:40:53:C1:FF:03:D4:15:98:F8:2F:39:59:A9:ED: 86:21:66:3E:F4:02:21:00:CF:FA:70:70:9B:DF:E0:09: 13:A5:3C:5C:F0:FE:9B:0E:AE:3B:43:F1:B9:D8:7A:87: 2C:65:EA:8F:0C:BA:AF:3B Signed Certificate Timestamp: Version : v1 (0x0) Log ID : 6C:FE:50:19:43:A8:5E:A9:16:BC:52:D1:33:E4:DC:C9: 1E:F1:41:1C:7D:25:84:20:D1:73:80:9E:18:18:EB:3A Timestamp : Aug 29 01:07:00.032 2026 GMT Extensions: 00:00:05:00:29:33:DC:CF Signature : ecdsa-with-SHA256 30:44:02:20:77:FE:8A:2D:B3:1C:D1:BB:6D:EC:38:E6: 90:C5:F0:58:EA:DD:AA:16:8F:5D:A0:78:C4:3B:DD:9D: C7:8D:2A:44:02:20:21:4C:0B:5F:66:73:E8:0A:2F:57: 0B:FB:34:57:AC:F5:5C:C6:A5:B0:FA:05:87:EC:08:25: A6:19:03:5D:D9:01
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

Cipher: TLS_AES_256_GCM_SHA384 · Checked 2026-10-07T08:14:55+00:00

Server-presented chain · 2 additional certificates

Chain certificate 1

Subject
C=US O=Let's Encrypt CN=YR2
Issuer
C=US O=ISRG CN=Root YR
Valid from
2025-09-03T00:00:00+00:00
Expires
2028-09-02T23:59:59+00:00
Days remaining
696
Serial (hex)
4EBD24947E24D394802D84A52FD5B319
Signature
RSA-SHA256
Public key
RSA 2048

Subject alternative names (SAN)

No SAN extension was presented.

SHA-256 fingerprint

23:8B:85:A0:09:9C:65:B9:70:47:7D:57:24:F1:A1:D4:75:CE:50:58:CF:FE:4E:FA:87:33:89:9B:DB:86:3C:47
Certificate extensions & PEM
keyUsage
Digital Signature, Certificate Sign, CRL Sign
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:TRUE, pathlen:0
subjectKeyIdentifier
40:15:2D:26:79:ED:32:20:9E:DF:9A:72:1D:D6:32:1F:81:0C:81:0C
authorityKeyIdentifier
DE:E7:5B:60:D0:22:6D:40:28:7D:3F:0D:01:FE:A4:B5:52:B4:51:94
authorityInfoAccess
CA Issuers - URI:http://yr.i.lencr.org/
certificatePolicies
Policy: 2.23.140.1.2.1
crlDistributionPoints
Full Name: URI:http://yr.c.lencr.org/ 
-----BEGIN CERTIFICATE-----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==
-----END CERTIFICATE-----

Chain certificate 2

Subject
C=US O=ISRG CN=Root YR
Issuer
C=US O=Internet Security Research Group CN=ISRG Root X1
Valid from
2026-05-13T00:00:00+00:00
Expires
2032-09-02T23:59:59+00:00
Days remaining
2157
Serial (hex)
F24B6D17F9D9AD7CB1C9FEA78782699F
Signature
RSA-SHA256
Public key
RSA 4096

Subject alternative names (SAN)

No SAN extension was presented.

SHA-256 fingerprint

07:26:39:D0:B1:40:D5:BF:FA:E1:6A:D9:C3:F6:CC:60:86:04:06:21:F5:1E:E6:1A:6D:46:A8:91:5C:07:CF:76
Certificate extensions & PEM
keyUsage
Certificate Sign, CRL Sign
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:TRUE
subjectKeyIdentifier
DE:E7:5B:60:D0:22:6D:40:28:7D:3F:0D:01:FE:A4:B5:52:B4:51:94
authorityKeyIdentifier
79:B4:59:E6:7B:B6:E5:E4:01:73:80:08:88:C8:1A:58:F6:E9:9B:6E
authorityInfoAccess
CA Issuers - URI:http://x1.i.lencr.org/
certificatePolicies
Policy: 2.23.140.1.2.1
crlDistributionPoints
Full Name: URI:http://x1.c.lencr.org/ 
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

One endpoint on port 443. Server-presented chain; no revocation, OCSP, CT or full TLS security scan.

View certificate JSON

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