certdesk

Check one domain's TLS certificate and return a verdict: status OK | WARN | CRITICAL | UNKNOWN, judged from the certificate chain the server actually serves. Measured from Korean point A (full chain and CRL revocation) plus Korean point B and an overseas point on the Globalping public measurement network (per-point results in measuredFrom; disagreement between points is a WARN). Checks: verification (expired, not yet valid, hostname mismatch, self-signed, untrusted root, missing intermediate, revoked via CRL), days left, renewal point, a newer certificate issued but not deployed (CT logs), the served chain, which old platform versions trust its root or cross-signs (compat: oldest Android, iOS, macOS, Windows, Java and Firefox versions), and the issuing CA's incident history. If the server cannot be measured the status is UNKNOWN and CT logs are shown only as an estimate, never as OK. Set detail=true to include the full chain in the text output.

DNS and hosting facts for a domain: nameservers with DNS provider, A/AAAA with IP owner (ASN), CNAME, MX, CAA (which CAs may issue), SPF/DMARC, DNSSEC, registrar and domain expiry (RDAP).

Compare answers for one DNS record across resolvers: the authoritative nameservers, Korean ISPs (KT, SK Broadband, LG U+) and public resolvers (Cloudflare, Google, Quad9, OpenDNS), measured from a Korean network. Use it to confirm a TXT/CNAME for certificate domain validation (e.g. _acme-challenge) has propagated.

Verdict for up to 5 domains at once: status OK | WARN | CRITICAL | UNKNOWN per domain combining the served certificate (verification, days left, null when the server cannot be measured) and domain registration expiry (RDAP), plus Korean alert lines. Use this for inventories, CI gates (fail unless status is OK) and periodic checks.

Security posture check of a web server (no port scanning): TLS protocol support (legacy 1.0/1.1 detection via a Korean network probe), security headers (HSTS/CSP/X-Content-Type-Options/anti-clickjacking/Referrer-Policy), HTTP→HTTPS redirect, and certificate key/signature strength. Returns per-item pass/warn/fail and an overall grade.

Explain a TLS/SSL certificate error message from a browser, curl/OpenSSL, Java, Python, Node.js, Go or .NET: likely causes, fixes, and links to step-by-step guides (Korean). Works offline from a curated knowledge base.

Subscribe an email address to free daily expiry monitoring of up to 5 domains (certificate, domain registration and security grade) with email alerts, plus an optional Slack/Discord/Telegram/webhook channel. Also alerts when Certificate Transparency logs show a new certificate for a domain from a CA not seen before (possible unauthorized issuance). Double opt-in: a confirmation email is sent and monitoring starts only after the recipient clicks the link; one confirmation email per address per 24 hours. Use only an address the user owns and explicitly asked to use.