Know the moment a certificate is issued for your domain
Alert24 watches public Certificate Transparency logs and tells you instantly when a new SSL certificate appears for your domain or subdomains — an early warning for phishing and impersonation. One Domain monitor also tracks DNS changes, registration expiry, and SSL expiry.
From domain name to early warning in minutes
Point Alert24 at your domain
Add a Domain monitor and enter your domain. Choose which DNS record types to watch and set your expiry thresholds.
A baseline is established
We snapshot your DNS records, read your registration and SSL expiry dates, and capture the certificates already in CT logs.
Define your expected issuers
Add the certificate authorities you actually use (Let's Encrypt, your CDN, etc.) so routine renewals stay silent.
Get alerted on what matters
Unexpected new certificates, DNS changes, and approaching expiries raise alerts via email, escalation policies, and incidents.
One monitor. Four watchers.
A single Domain monitor in Alert24 watches everything that matters about a domain — so you don't have to stitch together four different tools.
Certificate Transparency monitoring
HeadlineWe continuously watch public CT logs (crt.sh and Cert Spotter) and alert you the instant a new SSL certificate is issued for your domain or any subdomain. An expected-issuer allowlist keeps routine Let's Encrypt and CDN renewals silent — so a certificate from an unexpected issuer becomes a high-signal early warning for phishing and domain impersonation.
DNS change detection
Alert24 snapshots your A, AAAA, MX, NS, TXT, CNAME, and CAA records (each record type is opt-in) and alerts you when they change unexpectedly. This catches DNS hijacking, SPF/DKIM/DMARC tampering, and subdomain takeover vectors before they're exploited.
Domain registration expiry
Using RDAP — no API keys, no scraping — we track your domain's registration expiry and detect the registrar. You get warned well before it lapses (configurable threshold, default 30 days), so a forgotten renewal never takes your business offline.
SSL certificate expiry
Full certificate chain inspection with early expiry warnings. Catch an expiring or misconfigured certificate before browsers start throwing scary warnings at your customers.
Signal, not noise
Let's Encrypt renews your certificate every 60-90 days. Your CDN reissues certificates on its own schedule. You don't need an alert for any of that. Most certificate monitoring drowns you in routine renewals until you stop reading the emails — exactly when a real threat slips through.
Alert24's expected-issuer allowlist flips that around. You tell us which certificate authorities you legitimately use. Renewals from those issuers stay silent. A certificate from any other issuer becomes a high-signal alert — because that's the one that might be a phishing site impersonating your brand.
Expected issuer renews
Silent. No alert, no inbox fatigue.
Unexpected issuer appears
Security event raised. Your team gets notified.
Who needs domain & certificate monitoring
Security teams
A certificate issued for login.yourbrand.com that you didn't request is often the first observable sign of a phishing or impersonation campaign. CT monitoring turns that into an alert instead of a customer report.
Agencies & MSPs
Managing dozens of client domains? Watch every domain's certificates, DNS, and renewal dates from one place — and look like a hero when you catch the issue first.
SaaS companies
Wildcard certs and sprawling subdomains make takeover and shadow-cert issuance easy to miss. DNS snapshots plus CT monitoring close the gap.
E-commerce
An expired domain or SSL certificate during a sale is catastrophic. RDAP-based expiry tracking and chain inspection make a lapsed renewal nearly impossible.
How Alert24 compares
Public tools like crt.sh let you look up certificates manually, but they don't watch your domain or alert you. Alert24 brings every watcher together and routes the findings into your existing alerting.
| Capability | Alert24 | Standalone CT monitoring tools | DNS / registrar dashboards |
|---|---|---|---|
| Alerts on newly issued certificates (CT logs) | — | ||
| Expected-issuer allowlist to suppress renewal noise | — | — | |
| Covers subdomains and wildcards | — | ||
| DNS change detection (A/AAAA/MX/NS/TXT/CNAME/CAA) | — | — | |
| Domain registration expiry (RDAP) | — | ||
| SSL certificate chain & expiry inspection | — | — | |
| Security events that don't mark your domain 'down' | — | — | |
| Routes into escalation policies & incidents | — | — | |
| Combined with uptime & status pages | — | — | |
| Included in every plan (no per-feature add-on) | — | — |
Comparison reflects the structural difference between an integrated monitoring platform and single-purpose tools. Capabilities of specific third-party products vary by plan.
Frequently asked questions
What is Certificate Transparency monitoring?
Certificate Transparency (CT) is a public, append-only log of every SSL/TLS certificate issued by participating certificate authorities. Alert24 watches these logs (via crt.sh and Cert Spotter) and notifies you whenever a new certificate appears for your domain or its subdomains. Because any certificate issued for your domain shows up in CT, it's a powerful early-warning signal for phishing sites and domain impersonation.
Won't I get spammed every time my certificate renews?
No. Let's Encrypt renews your certificate every 60-90 days, and CDNs reissue certificates routinely — you don't need an alert for that. Alert24 uses an expected-issuer allowlist: list the certificate authorities you actually use, and routine renewals from those issuers stay silent. You only get alerted when a certificate is issued by an unexpected issuer.
Do I need API keys or third-party accounts?
No. Domain registration expiry uses RDAP, certificate data comes from public CT logs and direct chain inspection, and DNS is read directly. There are no API keys to manage and nothing to install — just enter your domain.
Does this work for subdomains and wildcards?
Yes. CT monitoring covers your domain and its subdomains, so a certificate issued for an unexpected subdomain (a common phishing and takeover pattern) will trigger an alert. DNS snapshotting covers the records you opt into monitoring.
What DNS records can Alert24 monitor?
A, AAAA, MX, NS, TXT, CNAME, and CAA records. Each record type is opt-in, so you can watch exactly what matters — for example MX and TXT to catch mail (SPF/DKIM/DMARC) tampering, or NS to catch a domain hijack.
How are these alerts handled differently from downtime?
DNS changes and newly issued certificates raise security events with their own severity — they do not mark your domain as 'down'. Alerts flow through email, your escalation policies, and can open incidents, so the right people are notified without polluting your uptime metrics.
Watch your domain before someone else does
Certificate Transparency monitoring, DNS change detection, domain expiry, and SSL expiry — included in every Alert24 plan. No API keys, no credit card required.