Uptime Monitoring

Uptime monitoring that catches what others miss

Uptime monitoring polls your websites, APIs, and services on a schedule. It alerts you when they stop responding. The basic case — checking if a page loads — is easy. Any tool does it.

The hard cases are where real downtime hides:

• HTTPS certificate expires at midnight on Sunday
• Domain lapses because the registrar's card got rotated
• API returns HTTP 200 with corrupted JSON for three hours
• CDN silently changes IP and breaks DNS-pinned upstream
• Cron job stopped working last Tuesday and nobody knows

DiagnoSEO Uptime Monitoring handles all these cases in one tool. Checks run from 13 regions worldwide. Alerts route to email, Telegram, Slack, Discord, or SMS — wherever you actually look.

For SEO professionals, this doubles as SEO infrastructure monitoring. A domain that expires deindexes overnight. An SSL warning kills organic traffic. A broken redirect chain leaks link equity. The same tool that catches downtime also catches the silent issues that erode rankings.

What you get

• 11 monitor types — HTTP(S) website checks, keyword presence or absence, ping (TCP), TCP port, heartbeat and cron-job monitoring, custom HTTP API with method, headers, body and JSON assertions, multi-location checks from 13 countries, SSL certificate watchdog, DNS change detection, domain expiration tracking, and response time threshold alarms.
• Real-time alerts — email, Telegram, Slack, Discord, and SMS. A configurable confirmation period (consecutive fails) so a momentary blip does not wake you at 3 a.m. Quiet hours so you sleep. Recovery (UP) alerts so you know when it is safe to put the phone down.
• SSL and domain expiry warnings — automatic 30/14/7/3/1-day reminders before expiration. Color-coded pills in the dashboard. Never get caught by a midnight SSL expiry again.
• DNS change detection — alert when your A, AAAA, MX, NS, or CNAME records change. Useful for catching unauthorized DNS hijacks, accidental misconfiguration during migrations, or third-party providers updating endpoints without notice.
• Multi-location checks — verify your site is up from the US, UK, Germany, France, Italy, Spain, Poland, the Netherlands, Canada, Australia, Japan, Brazil, and India. Catches geo-routing issues, regional DNS problems, and ISP-level blocks.
• 30-day uptime bar chart and sparkline — see at a glance which sites have stability problems. Each daily bar is color-coded (green ≥99%, light green ≥95%, orange ≥50%, red <50%). The sparkline shows the last 50 response times with red dots marking outages.
• SLA reports — exportable CSV with uptime percentage, total downtime minutes, incident count, and mean time to recovery. Per monitor and aggregated.
• Heartbeat and cron-job monitoring — instead of pinging your server, your cron job pings us. If we do not hear from it within the expected window plus a grace period, we alert you. Catches silent cron failures (locked-out user, broken script, full disk) that traditional uptime monitoring misses.
• Bulk add via paste — drop 100 URLs into a textarea, press Save. Each line can include keyword:, interval:, tag:, and name: parameters. No CSV gymnastics.
• Tags and filters — group monitors by environment (prod, staging), team (api, marketing), or criticality (critical, optional). Filter the dashboard down to what matters right now.
• Browser-side queue processor — when you click "Check all now", the browser processes the queue in batches of 20, in parallel with the cron. So 200 monitors get checked in about 1 minute total, not 30 minutes.
• JSON assertions — for API monitoring: data.status must equal ok, result.count must be > 0, and so on. Catches APIs that return HTTP 200 with malformed payloads (the worst kind of broken).

Who uses uptime monitoring

Uptime monitoring vs UptimeRobot, Pingdom, BetterStack, Oh Dear, Site24x7, and StatusCake

The major competitors all do basic HTTP uptime well. Where they diverge is in adjacent features: SSL warnings, domain expiry tracking, DNS change detection, multi-region coverage from non-Western regions, JSON assertions, cron-job heartbeats, and free plan limits.

Below is a side-by-side comparison based on each tool's published pricing. Verify against the vendor's current page before making a buying decision. For detailed head-to-head breakdowns, see the per-competitor comparison pages linked below the table.

Frequently asked questions

• How fast does uptime monitoring detect an outage?

  It depends on your check interval and confirmation threshold. On Pro and Enterprise plans the check runs every 1 minute. The default confirmation threshold is 2 consecutive failures, so a sustained outage triggers an internal status change within about 2 minutes.

  Email alerts are throttled to 2 hours of sustained downtime to suppress short flaps. Short outages stay quiet; real outages get notified. Telegram, Slack, Discord, and SMS can be configured to fire on the immediate status change instead.

• What is the difference between uptime monitoring and synthetic monitoring?

  Uptime monitoring polls a single endpoint and verifies the response (status code, content, JSON shape). Synthetic monitoring runs multi-step browser scripts: log in, navigate, click checkout, fill a form.

  DiagnoSEO does uptime monitoring with deep response inspection (HTTP method, headers, body, JSON assertions, keyword presence). It does not do full browser scripting. For the majority of "is the site working" questions, this is the right tool. For multi-step user journey testing, use a dedicated synthetic tool alongside.

• Does uptime monitoring affect SEO?

  Yes — directly. Google's crawlers treat extended downtime as a quality signal. A site that fails to respond for hours during Googlebot crawls loses crawl budget and may have pages deindexed.

  Beyond raw uptime, the related signals matter just as much. Expired SSL certificates cause browser warnings that tank click-through rates. An expired domain triggers DNS NXDOMAIN responses that drop all rankings within days. A misconfigured redirect chain leaks link equity. Treating monitoring as part of SEO infrastructure (not just sysadmin tooling) catches these issues before they cost rankings.

• Why monitor SSL certificates separately if my host auto-renews?

  Because auto-renewal silently fails more often than people expect. Common causes:

  • Let's Encrypt rate limits hit during deployment
  • Certbot misconfiguration after a server upgrade
  • DNS-01 challenges failing because a CNAME got removed
  • Expired credit card on a commercial CA account

  All of these break renewal without throwing a visible error until the existing cert expires. SSL monitoring catches the silent failure 30 days before users do.

• Can I monitor an API that requires authentication?

  Yes. Configure the monitor with custom HTTP headers — typically an Authorization header with a Bearer token or API key. Header values are encrypted at rest in the database.

  For Basic Auth, there is a dedicated username/password field that signs the request automatically. For OAuth flows that need token refresh, use a long-lived service token or rotate the monitor's stored header on your end when needed.

• How does keyword monitoring work?

  You provide a string (or HTML fragment). The monitor fetches the response body and checks whether the string appears as a substring. Both plain text ("Add to cart") and HTML snippets (<button class="buy">) work.

  Two modes:

  • Must be present — fail if missing. Useful for verifying that page content loaded correctly.
  • Must be absent — fail if present. Useful for catching error pages that return HTTP 200, or detecting unauthorized content on your domain.
• Will I be charged credits for failed checks?

  No. Failed and successful checks cost the same — a check is a check regardless of outcome. Manual rechecks (the Refresh button) are free and do not draw from your check budget.

  WHOIS lookups for domain expiry are limited to once per 24 hours per domain to keep API costs predictable. The Force Fresh button bypasses this cap when you need an immediate re-check.

• What happens if a domain I monitor expires?

  The domain expiry monitor will have warned you 30, 14, 7, 3, and 1 days out via email — plus Telegram, Slack, and Discord if you have those configured.

  If you ignore all warnings and the domain expires, the HTTP monitor starts failing (DNS resolution returns NXDOMAIN). You will get a DOWN alert after the 2-hour sustained-failure threshold. At that point the domain is in the registrar's grace period (typically 30 days for most TLDs) and renewal is still possible.

• Is uptime monitoring GDPR compliant?

  DiagnoSEO Uptime Monitoring stores monitor configuration (URLs, headers, keyword strings) encrypted at rest using AES-256. Check results (response codes, timing, error messages) are stored for the retention period defined by your plan.

  No personally identifiable end-user data is collected from your monitored sites. The monitor reads only HTTP response headers and the body string you configured a keyword check against. Data is hosted in EU data centers. Full DPA is available on request.