SSL certificate monitoring tools: 8 services compared for certificate expiration monitoring

Short answer: the best SSL certificate monitoring tool depends on whether you want certificates watched on their own or alongside uptime. StatusCake and AlertPing include certificate checks on every plan, Better Stack includes them on its free tier, UptimeRobot puts them behind a paid plan, Site24x7 adds revocation checking, and Zabbix or Prometheus do it free if you are willing to host and maintain the stack yourself. All eight below check expiry from a real TLS handshake rather than a file on disk, which is the part that matters.

Check a certificate first ▸

Last updated August 2026 · US dollar list prices

alertping ▸ run check

live

▸ type a domain and run a real-feel check

▸ probes from 3 regions · FRA · IAD · SIN

▸ waiting…▌

If ever goes down, you get:

Alert fired ▸ 2 channels · 6.2 s after first failure

AlertPing app

● DOWN : HTTP timeout confirmed from 3/3 regions (FRA, IAD, SIN). Incident opened.

sms · on-call

AlertPing: DOWN. Confirmed 3/3 regions . First fail: Frankfurt.

the comparison

Eight SSL certificate monitoring tools, side by side

The split that actually decides this is whether certificate monitoring is a feature of something you already pay for, or a product you buy on its own. For most US teams it is the former, which is why the "included on which plan" column below is the one to read first.

Tool	Certificate checks included on	What it actually validates	Entry price (USD)	Best for
AlertPing	Every plan, including the $19 entry plan	Expiry, chain, hostname match, protocol, on every uptime check	$19/mo flat (20 monitors)	Teams who want certificate and downtime alerts on one flat bill
StatusCake	Every package, free tier included	Expiry dates with reminders at 30, 14 and 1 day	Free (1 SSL test), Superior $24.49/mo	Agencies watching a lot of domains cheaply
Better Stack	Free and paid plans	Dedicated TLS monitor type covering expiry and chain	Free (10 monitors)	Teams who also want on-call scheduling and log storage
UptimeRobot	Paid plans only, not the free tier	Certificate expiry and domain expiry alongside uptime	$10/mo monthly, $9/mo billed annually	People already running their uptime checks there
Site24x7	Paid plans, from the entry web uptime plan	Expiry plus OCSP and CRL revocation status, which most skip	From $10/mo	Teams who need revocation checking and wide protocol coverage
Datadog Synthetics	Paid add-on to the platform	Full TLS handshake, chain and expiry inside API tests	Usage priced per test, on top of Datadog	Shops already standardized on Datadog
Zabbix	Self-hosted, no license cost	Agent 2 WebCertificate plugin returns validity dates natively	Free software, you pay in hosting and time	Teams already operating a Zabbix server
Prometheus + Blackbox Exporter	Self-hosted, no license cost	probe_ssl_earliest_cert_expiry from a real handshake	Free software, needs Alertmanager and Grafana	Kubernetes and Prometheus shops

Prices are US dollar list prices. Vendor sites render prices in the visitor's local currency, so a figure you see from outside the United States may not match the numbers above. Where a tool sells annual billing at a discount, both figures are shown.

why this got urgent

Certificates now expire in 200 days, and that number keeps falling

Until March 2026 a public TLS certificate could be valid for 398 days, so a renewal you handled by calendar reminder came around roughly once a year. Under CA/Browser Forum ballot SC-081, that ceiling dropped to 200 days on March 15, 2026, and it drops again on a published schedule.

By 2029 a certificate lives 47 days. A process that worked at one renewal a year becomes roughly eight renewals a year on the same hostname. Every one of those is a new chance to install the leaf without its intermediates, to renew on the origin but not the CDN edge, or to renew the hostname you remember and forget the API subdomain. Monitoring stops being a nice-to-have at that cadence because the failure rate scales with the number of renewals.

Full detail on the schedule and what it changes for renewal automation is in our guide to the 200-day SSL certificate validity limit.

In effect from	Maximum certificate lifetime	Renewals per year, per hostname
Before March 15, 2026	398 days	About 1
March 15, 2026 (current)	200 days	About 2
March 15, 2027	100 days	About 4
March 15, 2029	47 days	About 8

Domain control validation reuse shrinks on the same timetable, so the revalidation work rises with the reissue work. Teams running automated issuance through ACME absorb this comfortably. Teams renewing by hand, or renewing anything an ACME client cannot reach, feel it immediately.

buying criteria

What separates a real certificate monitor from an expiry reminder

Plenty of tools will email you a date. Far fewer catch the failures that actually take a site down, because those failures happen after a successful renewal.

It reads the served certificate

The certificate on disk and the certificate your visitors receive are not always the same one. A monitor that opens a real TLS connection catches the case where the renewal succeeded but the web server, load balancer or CDN never reloaded it.

It validates the chain, not just the date

A missing intermediate is the classic post-renewal break. Desktop Chrome often papers over it with a cached intermediate while mobile clients and API consumers fail hard, so the problem looks intermittent until someone checks properly.

It covers hostnames nobody visits

Certificates on api., webhooks. and internal admin hosts expire quietly because no human is looking at them. Check how many certificate targets a plan includes before you buy, since that limit is usually separate from the uptime monitor limit.

It escalates, not just notifies

A 30-day warning that lands in a shared inbox during a busy sprint is a warning you will miss. What you want is a ladder: early email, then Slack, then SMS as the date closes in and the window to act shrinks.

It survives your own outage

Self-hosted monitoring that runs in the cluster it monitors will be down exactly when you need it. That is the honest cost of the free Zabbix and Prometheus options, and the reason hosted tools keep winning this category.

It checks more often than the warning window

A daily certificate check is fine for expiry, which moves slowly. It is not fine for a chain that broke ten minutes ago during a deploy. Tools that read the certificate on every uptime check catch both classes of failure with one monitor.

tool by tool

Where each one is genuinely the right answer

AlertPing

Certificate monitoring is part of every plan rather than a tier upgrade, and the certificate is read on every uptime check, so a chain that breaks mid-deploy surfaces in minutes instead of on tomorrow's daily scan. Warnings run at 30, 14, 7 and 1 day before expiry across email, Slack, SMS and webhook. Pricing is flat: $19 a month for 20 monitors, with 30-second checks from the $59 Team plan.

Where it loses: there is no free plan, no page speed monitoring, no domain expiry tracking and no APM. If you want certificate lifecycle management with issuance and private CA inventory, this is the wrong category of product entirely.

How our SSL certificate monitoring works ▸

StatusCake

The best value if you are watching a large number of domains. SSL testing is in every package including the free tier, with reminders at 30, 14 and 1 day, and the Superior plan at $24.49 a month ($20.41 billed annually) covers 50 SSL tests alongside 100 uptime tests, page speed and domain expiry. For an agency holding client sites, that is a lot of coverage on one invoice.

Where it loses: certificate tests run on their own slower schedule rather than with every uptime check, and 30-second uptime checks only arrive on the $79.99 Business tier.

StatusCake alternative, compared honestly ▸

Better Stack

Better Stack, formerly Better Uptime, has a dedicated TLS monitor type and offers it on the free plan, which covers 10 monitors at 3-minute checks. The real reason to pick it is the rest of the product: on-call scheduling and log management sit in the same account, so certificate alerts land in the same rotation as everything else.

Where it loses: the modular pricing adds up quickly once you pass the free tier, because monitors, responder seats and heartbeats are billed as separate blocks. Estimating next year's bill takes effort.

Better Stack alternative, compared honestly ▸

UptimeRobot

Certificate and domain expiry alerts sit on the paid plans, starting at $10 a month billed monthly or $9 billed annually for 10 monitors. If your uptime checks already live here, adding certificate coverage is the cheapest path available and takes about a minute to configure.

Where it loses: the well-known free tier does not include certificate monitoring, which surprises people. SMS is sold as credits rather than included, so an expiry escalation to a phone costs extra.

UptimeRobot alternative, compared honestly ▸

Site24x7

The one mainstream tool that checks revocation status through OCSP and CRL rather than stopping at the expiry date. If you work somewhere that has to prove a revoked certificate would be caught, that single feature decides the purchase. Web uptime monitoring starts around $10 a month, with the platform sold as a base plan plus metered add-ons.

Where it loses: the add-on model makes the real monthly cost hard to predict, and 30-second polling is reserved for the top enterprise tier.

Site24x7 alternative, compared honestly ▸

Zabbix and Prometheus (open source)

Both do this properly and neither charges a license fee. Zabbix Agent 2 ships a WebCertificate plugin that returns validity dates natively, so the shell scripts people used to bolt on are no longer needed. Prometheus pairs Blackbox Exporter with Alertmanager, exposing probe_ssl_earliest_cert_expiry from a genuine TLS handshake, which you then alert on with a threshold rule and graph in Grafana.

Where it loses: you own the uptime of your own monitoring. If the cluster running Blackbox Exporter is the thing that fails, nothing tells you. These are excellent choices when the stack already exists and poor ones when you are standing it up purely to watch certificates.

questions people ask

SSL certificate monitoring questions

What is SSL certificate monitoring?

SSL certificate monitoring is an automated check that connects to your HTTPS endpoints, reads the certificate they actually serve, and alerts you before it expires or when it stops validating. Good monitors check expiry date, the intermediate chain, hostname match and protocol, because a renewed certificate can still break on any of those.

How do I monitor SSL certificate expiration?

Add each HTTPS hostname to a monitoring tool as a certificate target, then set warnings at 30, 14, 7 and 1 day before expiry. Include every subdomain, not just the main site, and route the final warnings to SMS or Slack rather than email. Checking from outside your network matters, because internal clients often trust a chain that public visitors do not.

Is there a free SSL certificate monitoring tool?

Yes. StatusCake includes one SSL test on its free tier and Better Stack covers certificates on its free plan, while Zabbix and Prometheus with Blackbox Exporter are free to run if you host them. The limits are volume and escalation: free tiers cap you at one or a few certificates and rarely include SMS, which is the alert that gets answered at the weekend.

What is the best SSL certificate monitoring tool?

For most US teams the best tool is the one that already watches their uptime, since a separate certificate product is another vendor for one alert. Pick StatusCake for many domains on a small budget, Site24x7 if you need revocation checking, Better Stack if you want on-call built in, and AlertPing if you want certificate and downtime alerts on one flat monthly price.

Can Zabbix monitor SSL certificate expiration?

Yes, natively. Zabbix Agent 2 includes a WebCertificate plugin that connects to a host and returns the certificate's validity dates and validation result, so the custom UserParameter scripts older guides describe are no longer necessary. You still build the trigger and the escalation yourself, and you still have to keep the Zabbix server up.

How often should you check SSL certificates?

Daily is enough for expiry, which is predictable. It is not enough for validation failures, which appear the moment a deploy installs an incomplete chain or a load balancer serves a stale certificate. Tools that read the certificate on every uptime check catch that class of failure in minutes rather than up to 24 hours later.

Why did SSL certificate validity drop to 200 days?

The CA/Browser Forum passed ballot SC-081 in 2025 to shorten public TLS certificate lifetimes, limiting the damage window when a key is compromised and pushing the industry toward automated issuance. The cap fell from 398 to 200 days on March 15, 2026, drops to 100 days in 2027 and reaches 47 days in 2029.

What happens if my SSL certificate expires?

Browsers block visitors behind a full-page security warning and machine clients fail outright with no way to click through, so APIs, webhooks and mobile apps stop working first. The server is fine and the fix usually takes under 30 minutes. The expensive part is the hours before anyone notices, covered in our guide to an expired SSL certificate.

Certificate alerts on every plan, not a tier upgrade

AlertPing reads the certificate your visitors actually get on every check and warns you at 30, 14, 7 and 1 day, by SMS, email, Slack or webhook. Flat from $19 a month.

See pricing

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