Monitoring from 3 continents
Your SSL cert expires in 7 days.Would you know?
An expired certificate or lapsed domain is an instant, embarrassing outage — and it always happens on a weekend. CertSentry watches your certificates, domain registrations, DNS records and uptime, and alerts you days before anything breaks.
Free plan forever · No credit card required · Set up in 60 seconds
SSL certificate for client-site.com expires in 7 days
CertSentry → you, 09:00 · also sent to #ops on Slack
Renew before Tue, 16 Jun to avoid an outage. Auto-renew appears to have failed — the served certificate hasn't changed in 83 days.
Four ways your site breaks silently
CertSentry covers the failure modes that uptime-only tools miss until it's too late.
SSL expiry alerts
We open a real TLS connection, read the certificate, and warn you 30, 14, 7, 3 and 1 days before it expires — plus instantly on mismatched or self-signed certs.
Domain expiry alerts
Auto-renew silently failing is how good domains die. We watch registration expiry via RDAP/WHOIS so a lapsed card on file never takes your site down.
DNS change detection
A changed A record or hijacked nameserver is an incident. We snapshot A, AAAA, MX, NS, CNAME and TXT daily and alert on confirmed changes.
Multi-region uptime
Checks from North America, Europe and Asia. You're only paged when multiple regions agree across consecutive checks — no 3am false alarms from a network blip.
Pricing
Start free. Upgrade when you have more domains to protect.
Prices in USD, billed monthly via Stripe. VAT handled at checkout where applicable.
Frequently asked questions
›Why do I need this if my certs auto-renew?
Because auto-renew fails silently: an expired card, a changed DNS record breaking ACME validation, a forgotten subdomain on a different stack. CertSentry checks the certificate that's actually being served — if renewal broke, you hear about it a week early, not from a customer screenshot.
›How are alerts delivered?
Email on every plan. Pro and Agency add Slack and Telegram webhooks. Expiry alerts fire once per threshold (30/14/7/3/1 days by default — configurable per monitor), so you're never spammed.
›What counts as "down"?
A timeout, connection error, or non-2xx/3xx response. To avoid false positives we only declare an outage when at least 2 of 3 regions fail 2 consecutive checks, and we alert again the moment it recovers.
›Do you support client domains I don't own?
Yes — agencies monitor client domains all the time. Anything publicly reachable can be monitored; you don't need to install anything or verify ownership.
›Can I cancel anytime?
Yes. Billing runs on Stripe; you can upgrade, downgrade or cancel from the customer portal in two clicks. Your data can be exported or deleted at any time.
The next expiry email you get should be from us.
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