~/tools / ssl-checker

SSL Checker

Check SSL certificate expiry, chain validity, TLS version and cipher. Catches expired certs, weak crypto and chain issues.

[ OK ] Valid for 70 more days.

── output ─────

Issued to: *.fastmail.com
Issued by: R12
Valid from: 2026-04-02
Valid until: 2026-07-01 (70 days)
TLS version: TLSv1.3
Cipher: TLS_AES_256_GCM_SHA384
Key: RSA · 2048 bit
Signature: sha256WithRSAEncryption
Forward secrecy: yes
Self-signed: no
Must-staple: no
SHA-256 fingerprint: F5:F9:CF:A1:72:B3:33:BB:10:A5:D1:C9:C5:1B:3F:87:0D:B1:F1:FC:58:C5:4B:90:2C:6B:5A:16:1B:0F:BF:4D
Serial: 0525A95338C9EF8E0F3BAC5D5FF9A786A06C

subject_alt_names · 4

*.caldav.fastmail.com *.carddav.fastmail.com *.fastmail.com fastmail.com

certificate_chain · 2 certs

[ leaf ]*.fastmail.com

70 days left

issuer: R12

2026-04-02 → 2026-07-01

[ inter ]R12

325 days left

issuer: ISRG Root X1

2024-03-13 → 2027-03-12

// Save fastmail.com → we'll run this daily and alert on changes. /signup →