DNS
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

fastmail.com · 103.168.172.65:443

Verified

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

Subject
CN=*.fastmail.com
Issuer
C=US O=Let's Encrypt CN=YR2
Valid from
2026-09-14T00:20:06+00:00
Expires
2026-12-13T00:20:05+00:00
Days remaining
79
Serial (hex)
061783AF76B7B7CE0EBFD6F2F40C5002D26B
Signature
RSA-SHA256
Public key
RSA 2048

Subject alternative names (SAN)

DNS:*.api.beta.fastmail.com, DNS:*.api.dogfood.fastmail.com, DNS:*.api.fastmail.com, DNS:*.api.qa.fastmail.com, DNS:*.beta.fastmail.com, DNS:*.caldav.fastmail.com, DNS:*.carddav.fastmail.com, DNS:*.dogfood.fastmail.com, DNS:*.fastmail.com, DNS:*.qa.fastmail.com, DNS:fastmail.com

SHA-256 fingerprint

D1:76:4B:B6:D5:35:16:18:99:1B:42:5A:8F:37:B5:72:F4:4C:6D:FC:1E:6E:AD:40:36:90:B8:D8:4D:CF:89:6F
Certificate extensions & PEM
keyUsage
Digital Signature, Key Encipherment
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:FALSE
subjectKeyIdentifier
5A:06:31:2D:DE:91:8E:6C:2F:8B:7F:CD:5E:23:F4:E0:1F:B4:80:20
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:*.api.beta.fastmail.com, DNS:*.api.dogfood.fastmail.com, DNS:*.api.fastmail.com, DNS:*.api.qa.fastmail.com, DNS:*.beta.fastmail.com, DNS:*.caldav.fastmail.com, DNS:*.carddav.fastmail.com, DNS:*.dogfood.fastmail.com, DNS:*.fastmail.com, DNS:*.qa.fastmail.com, DNS:fastmail.com
certificatePolicies
Policy: 2.23.140.1.2.1
crlDistributionPoints
Full Name: URI:http://yr2.c.lencr.org/108.crl
ct_precert_scts
Signed Certificate Timestamp: Version : v1 (0x0) Log ID : D7:6D:7D:10:D1:A7:F5:77:C2:C7:E9:5F:D7:00:BF:F9: 82:C9:33:5A:65:E1:D0:B3:01:73:17:C0:C8:C5:69:77 Timestamp : Sep 14 01:18:37.138 2026 GMT Extensions: none Signature : ecdsa-with-SHA256 30:45:02:21:00:90:0A:EF:A8:44:33:D3:20:DD:1F:F4: 27:98:F2:60:05:6B:ED:67:5A:04:CA:8E:26:3C:CD:D7: 0D:A6:5B:98:7F:02:20:6B:DF:21:56:12:0C:36:08:A1: 6A:CD:F6:8A:11:4B:D7:AE:33:9E:C0:E5:1B:AD:38:77: 76:62:2E:38:7B:5D:9C 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 14 01:18:37.445 2026 GMT Extensions: 00:00:05:00:33:08:B8:1A Signature : ecdsa-with-SHA256 30:45:02:20:48:18:CE:96:A5:E8:73:99:DD:6D:1A:50: D5:8A:F1:D9:82:9A:63:F9:14:E9:CD:8B:03:D9:5B:98: 4C:41:A1:A7:02:21:00:94:C7:14:3C:C2:9E:CA:8B:7B: 6F:97:54:01:EF:90:7D:3F:A1:DC:94:BD:58:08:25:BB: 7F:C8:EF:EA:BC:07:DD
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

Cipher: TLS_AES_128_GCM_SHA256 · Checked 2026-09-24T23:19:57+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
709
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
2170
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-----
MIIF9DCCA9ygAwIBAgIRAPJLbRf52a18scn+p4eCaZ8wDQYJKoZIhvcNAQELBQAw
TzELMAkGA1UEBhMCVVMxKTAnBgNVBAoTIEludGVybmV0IFNlY3VyaXR5IFJlc2Vh
cmNoIEdyb3VwMRUwEwYDVQQDEwxJU1JHIFJvb3QgWDEwHhcNMjYwNTEzMDAwMDAw
WhcNMzIwOTAyMjM1OTU5WjAuMQswCQYDVQQGEwJVUzENMAsGA1UEChMESVNSRzEQ
MA4GA1UEAxMHUm9vdCBZUjCCAiIwDQYJKoZIhvcNAQEBBQADggIPADCCAgoCggIB
ANvGJnN78CTJdWL3+eGfsLN5TrNBJs+VH9hRXqRbwxu9sGNiB0BD1fcOxbSUQCJI
M1xE13Db+5Cw1w0s0EBYsvuIP/6joF0w8cuImbgR1OGgYbSQ4OpzI+DG8SGuTlcE
873OCS+kh3srlo6vl43M5OJg4Aeo1sfHp6kTJDoIiFBNJAY+OKfX/FUvYKuhjT+n
o49lmqmupSBI5PkBQiqrEGtWU5uxU/cQWHGu8jSjFBznZqvbNPLMXMLFxCb3WTfr
JBXXjqvWG+v4bjzxjjeAtOlU7qarRDvNOyAuQYLln904M+faKx8hnLCpJ15ZqaEg
cNlY+9MMWcC5yvL2A2j3l9+2buggZX+dOE91zYmIdawTvSZuVvlbRrAlLxIB6pwM
BjneXCjYQ8+3BCCjssbSNpZU3hTcBDdhfAlEDlYr6pEatnMdmDT5BqnKC92bd0Eh
M1fbLHioLccLCuievT8ZkPhZrq7Mii7gNXAcUEAR8+lzYal+9zTg7C5DALyVOeG/
CqfRAMn1KSHCR0NSA6P8tn/mGRlnCct5rtVCLnVySVpU6H1qGg3DgTOuskf8eahT
MiYbI5ezPJmO5ertalskQ1utp74+eDy92PI4ftHKTbq9IWhH4YZKh3WnJEIt+oQv
lYZbY8tpEroKrFB6PFGzrJIDRyts4HqvuH52RFj2zv/BAgMBAAGjgeswgegwDgYD
VR0PAQH/BAQDAgEGMBMGA1UdJQQMMAoGCCsGAQUFBwMBMA8GA1UdEwEB/wQFMAMB
Af8wHQYDVR0OBBYEFN7nW2DQIm1AKH0/DQH+pLVStFGUMB8GA1UdIwQYMBaAFHm0
WeZ7tuXkAXOACIjIGlj26ZtuMDIGCCsGAQUFBwEBBCYwJDAiBggrBgEFBQcwAoYW
aHR0cDovL3gxLmkubGVuY3Iub3JnLzATBgNVHSAEDDAKMAgGBmeBDAECATAnBgNV
HR8EIDAeMBygGqAYhhZodHRwOi8veDEuYy5sZW5jci5vcmcvMA0GCSqGSIb3DQEB
CwUAA4ICAQA8spSI95KKfn2W6GMmDpHBJSPaLbsS3W93cijJCRCYAc1fsJgL1FIL
7C0C9ecPOdcwB2fi0Dk2p94j9iTJCxmt5CFSKLRWwnXT2MMSXexVxqoVB79BdWPx
VXETkVme/qYSAuKVHh5Ps+5BixgmwS1JkjSAc+MfrUbNssVEEnH0aEiAh+rotXAV
JSP/Ye7LJPEwD9DWG72vVWbhAcuOf5OLjz57Ctk7MgQHynZ7+PlHJtajroCaIbtC
r6tcZZaAwUQm+jQyeWdV+2hv9deOYFmKeQyjjcSrN5Nadrw+L9DZJLbA1HqeNvLh
BgqpP0fvJq2N6EtD574N6eMI7uMsJTnji2UDz9el5XLSv9fqJMuDQtYVb2oTNoKp
oUqhxPVC0aq4eG5MESaIdn8b5ZGSSeAJLMHXljEdlNza+ncfkviXk1POLnnFdvx8
/gk6M374WbLWFXw8N141B/Rl/tINGfl1TxOIiqtiMYkL02RSGb1kq34BL9NPP27z
RGMuHGnzS3hFIrRTfKxrzUZ9RzQWzEG3K6fJ3r2nqSltkeytis9DIBoFY9VmVyjL
M71DMi+y1+TRSJVClEMwvA4yL++7q9XZx5r5wBRWB4kQTKH5qyoZnDw7iiuh1lID
yDFx8r7i9vIJU5HS3moZLkYWAOilMaV9N56A9Bgb6dNcHkvg3NoaYA==
-----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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