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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

optisprint.net · 212.233.128.16:443

Unverified
Certificate verification failed. These are unverified certificate details presented by the server. Peer certificate CN=`flight-school.bg' did not match expected CN=`optisprint.net'

Certificate verification failed

Subject
CN=flight-school.bg
Issuer
C=US O=Let's Encrypt CN=YR1
Valid from
2026-09-13T20:03:11+00:00
Expires
2026-12-12T20:03:10+00:00
Days remaining
70
Serial (hex)
0612545C35F3BC474ACF48D2501D6FAC39F3
Signature
RSA-SHA256
Public key
RSA 4096

Subject alternative names (SAN)

DNS:flight-school.bg, DNS:www.flight-school.bg

SHA-256 fingerprint

7D:1D:A5:9A:53:B4:E5:65:81:C9:7A:FC:1B:6F:75:55:A6:A3:02:E7:71:14:D4:62:91:AC:B2:3E:14:C0:5B:C8
Certificate extensions & PEM
keyUsage
Digital Signature, Key Encipherment
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:FALSE
subjectKeyIdentifier
3B:2D:75:D6:07:C6:3C:61:F2:4D:83:2C:54:CB:76:81:92:D7:01:91
authorityKeyIdentifier
1F:2F:35:BE:46:14:82:CD:40:B1:AE:79:2C:55:78:FA:F7:D4:68:FB
authorityInfoAccess
CA Issuers - URI:http://yr1.i.lencr.org/
subjectAltName
DNS:flight-school.bg, DNS:www.flight-school.bg
certificatePolicies
Policy: 2.23.140.1.2.1
crlDistributionPoints
Full Name: URI:http://yr1.c.lencr.org/116.crl
ct_precert_scts
Signed Certificate Timestamp: Version : v1 (0x0) Log ID : D8:09:55:3B:94:4F:7A:FF:C8:16:19:6F:94:4F:85:AB: B0:F8:FC:5E:87:55:26:0F:15:D1:2E:72:BB:45:4B:14 Timestamp : Sep 13 21:01:41.686 2026 GMT Extensions: none Signature : ecdsa-with-SHA256 30:44:02:20:44:3F:50:F7:FF:0B:BA:55:81:54:E8:B6: 18:AE:2D:0E:29:0A:C9:53:0E:21:DB:3C:64:E5:84:75: C0:48:1F:32:02:20:6E:DE:0F:E4:6D:74:5E:B6:38:49: 13:24:B3:C5:C1:79:E4:FA:D3:63:FD:DA:E3:CA:5D:C6: 24:94:8C:2E:AD:CA Signed Certificate Timestamp: Version : v1 (0x0) Log ID : A8:26:CB:E3:0A:C6:35:12:46:53:3F:E0:65:F1:4F:19: D9:6E:19:08:13:C4:1D:D9:6D:79:00:B3:12:3C:55:27 Timestamp : Sep 13 21:01:42.444 2026 GMT Extensions: 00:00:05:00:32:E4:B0:82 Signature : ecdsa-with-SHA256 30:46:02:21:00:E0:82:69:0A:0C:7D:C0:A2:D0:37:19: 80:B1:99:56:FC:FA:A7:E0:59:31:C8:F1:34:C8:33:AE: 1B:28:AD:AC:49:02:21:00:D6:20:D3:0B:16:93:D4:B2: DC:E9:E6:6B:FD:B7:6C:6E:38:5E:09:6C:DD:70:FD:FA: FE:4D:2D:67:89:EA:D3:69
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

Cipher: TLS_AES_256_GCM_SHA384 · Checked 2026-10-02T21:46:58+00:00

Server-presented chain · 2 additional certificates

Chain certificate 1

Subject
C=US O=Let's Encrypt CN=YR1
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
701
Serial (hex)
A20253F15F2691C05DC1CE13B9BCCA4E
Signature
RSA-SHA256
Public key
RSA 2048

Subject alternative names (SAN)

No SAN extension was presented.

SHA-256 fingerprint

13:94:96:34:D9:9C:D6:FD:6A:A8:0B:C0:34:FE:FA:CC:EB:19:69:FE:EF:98:65:86:71:3E:CD:BB:05:75:8D:3F
Certificate extensions & PEM
keyUsage
Digital Signature, Certificate Sign, CRL Sign
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:TRUE, pathlen:0
subjectKeyIdentifier
1F:2F:35:BE:46:14:82:CD:40:B1:AE:79:2C:55:78:FA:F7:D4:68:FB
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
2162
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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