Documentation

Everything you need to monitor your domains and SSL certificates.

Getting Started

DomainCat monitors your domain expiry dates, SSL certificates, DNS records, and email security (SPF / DMARC / DKIM) — and alerts you before anything expires or breaks.

Add your first domain

Click Add Domain in the top toolbar.

Enter a domain name (e.g. example.com) and click Add.

DomainCat immediately runs a full check — SSL, WHOIS, DNS, and email security — and shows you the results.

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Checks run automatically every 24 hours. You can trigger a manual re-check at any time from the domain detail panel.

Import multiple domains at once

Use the CSV Import button to bulk-add domains. Your CSV should have one domain per row in the first column (header row optional). Up to 500 domains per import on Pro plans.

Organising domains

Use Groups to organise domains by project, client, or environment. Use Tags for cross-cutting labels like production or staging. Both are filterable from the sidebar.

Domain Monitoring

DomainCat tracks domain registration expiry via WHOIS and shows you the registrar, expiry date, and days remaining.

Status indicators

ValidDomain is registered and expires in more than 30 days.

ExpiringExpires within 30 days — renewal recommended soon.

CriticalExpires within 7 days or WHOIS lookup failed.

UnknownWHOIS data unavailable — some TLDs have limited WHOIS coverage.

WHOIS coverage

DomainCat supports WHOIS lookups for all major TLDs (.com, .net, .org, .io, .co, .app, .dev and hundreds more). Some country-code TLDs (ccTLDs) restrict WHOIS access — these will show "Unknown" status.

SSL Monitoring

DomainCat connects to your domain on port 443 and retrieves the live SSL certificate — issuer, expiry date, days remaining, and whether the cert is valid for the domain.

SSL status indicators

ValidCertificate is valid and expires in more than 30 days.

ExpiringCertificate expires within 30 days.

CriticalExpires within 7 days, already expired, or invalid.

No SSLNo SSL certificate found, or port 443 is not reachable.

Certificates behind Cloudflare (edge vs origin)

If your site sits behind Cloudflare (or another CDN), there are actually two SSL certificates in play — and the one your browser shows you is not the one that usually takes your site down.

Why the padlock you see isn't the whole story

When a domain is proxied through Cloudflare, your visitors connect to Cloudflare, not to your server. So the certificate their browser sees — the green padlock — is Cloudflare's edge certificate. Cloudflare renews that one automatically, so it basically always looks fine.

Meanwhile, your own server still has its own certificate (the "origin" cert) sitting behind Cloudflare. That's the one you actually manage, and that's the one that quietly expires at 2am and you never find out — because the padlock in the browser still looks green. A free SSL checker that just loads your site will tell you everything's fine right up until it isn't.

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Edge cert = what browsers see (Cloudflare's, always valid). Origin cert = the one on your real server, behind the CDN — the one that actually breaks. DomainCat watches both.

What DomainCat does about it

When we detect that a domain is proxied, we label it honestly — the SSL tab shows the edge cert with a "Proxied" badge — and then we try to watch your origin cert too, separately, so an expiring origin cert can't sneak past you behind a healthy-looking edge.

What we need from you

Cloudflare hides your origin server on purpose, so we can't find it automatically from your domain. To watch your origin cert, tell us where your server actually is:

Open the domain, go to the SSL tab, and find the Origin certificate section.

Enter your origin server's IP address (or a direct, un-proxied hostname like origin.example.com) and hit Save. You can also fill in the "Origin server" field when you first add the domain.

That's it — we'll start checking your origin cert on every cycle and alert you the same way we do for normal certs (30 / 14 / 7 days and expired).

Not sure of your origin IP? It's usually in your Cloudflare DNS settings (the "real" IP behind the orange cloud), or from your hosting provider / server control panel.

When we honestly can't see it

Sometimes we can't reach your origin — and when that happens we tell you straight instead of showing a misleading green check:

Not monitoredThe domain is behind a CDN but you haven’t told us where the origin is yet. Add it to turn monitoring on.

UnreachableWe know your origin’s address but can’t connect — usually because it only allows Cloudflare’s IPs. Allowlist our prober IP (shown in the app) on your origin firewall and we’ll be able to check it.

Confirm?We found a likely origin by looking at your DNS, but we won’t monitor a guess — confirm it’s really your server first, so a wrong guess never gives you false confidence.

MonitoredWe’re actively watching your origin cert and will alert you before it expires.

The whole point: we promised we won't let your cert expire without you knowing. If there's something we genuinely can't see, we'd rather show you the gap — and how to close it — than pretend everything's green.

Notifications

DomainCat sends email alerts when domains or SSL certificates are approaching expiry. Alerts are sent at 30 days, 14 days, and 7 days before expiry.

Configure notification email

Go to Settings (gear icon, top right).

Under Notifications, enter the email address(es) you want alerts sent to.

Click Save. A confirmation email will be sent to verify the address.

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By default, alerts go to your login email. You can add additional addresses (e.g. a shared team inbox) in Settings.

Billing

Starter$9/mo

✓Up to 10 domains
✓Daily checks
✓SSL + WHOIS + DNS
✓Email alerts
✓Email support

Pro$29/mo

✓Unlimited domains
✓Daily checks
✓SSL + WHOIS + DNS + Email security
✓Email alerts
✓CSV import
✓Priority support

Troubleshooting

Domain / SSL issues

Account issues

Still stuck?

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Email [email protected] with your domain name and a description of the issue. We'll respond within one business day.