Catch website issues
uptime tools miss.
Visual Sentinel checks your pages like a visitor: uptime, SSL, DNS, speed, content, and visual changes. Get alerted when a page goes down, slows down, or looks wrong.
What is website monitoring?
Website monitoring is the practice of automatically and continuously checking a website to verify it is online, fast, reachable, and visually correct. A modern website monitoring tool runs scheduled checks from one or more regions, captures evidence (response times, screenshots, content snapshots, certificate health), compares each result against a known baseline, and alerts the right people when something deviates.
The phrase covers a range of intent. Uptime monitoring is the cheapest version: a single check that the URL responds successfully. Web page monitoring extends that with performance metrics. Full website monitoring (also called six-layer or website observability) adds SSL certificate health, DNS resolution, visual regression, and content change detection. The depth at each layer is what separates a website monitor that catches real problems from one that just confirms a server is on.
Every important signal.
One monitor.
Uptime, SSL, DNS, speed, content, and visual checks work together so you can see what changed and where to look first.
Uptime
HTTP / HTTPS / PING / PORT / TCP checks at intervals from one minute to one hour, from multiple regions, with cross-region confirmation to suppress local network blips.
Performance
Time-to-first-byte, total load time, transfer size, and Core Web Vitals tracked on every check. Alert when a page degrades past your threshold so you catch slow regressions before customers complain.
SSL & TLS
Certificate issuer, validity dates, SAN list, key algorithm, and full chain on every HTTPS check. Configurable expiry warnings (30 / 14 / 7 days). Catch chain misconfigurations and rogue intermediates.
DNS
A, AAAA, MX, NS, TXT, CNAME, and SOA records snapshotted on every check. Detect DNS hijacking, accidental record changes, propagation issues, and expiring nameservers. Cloudflare-integrated customers also see the real origin IP behind the proxy.
Visual
Full-page screenshot on a real Chromium browser, compared pixel by pixel against a baseline. Configurable mismatch threshold so dynamic content (ads, timestamps) does not trigger alerts. Catches CSS regressions, missing images, and injected content.
Content
Text-level diff of page content between checks. Detect accidental copy deletions, missing call-to-action buttons, price changes, and stale caches. Configurable keyword assertions for custom rules.
A page can be reachable
and still fail the customer.
A reachable page can still be broken
A basic uptime check says the URL responded. It does not prove the page rendered, the certificate chain is healthy, DNS still points where expected, or the layout is intact. Visual Sentinel checks the visitor-facing page and the signals around it.
Single-region checks miss real outages
Status checks from a single location flag every regional network blip as a global outage. Visual Sentinel runs checks from multiple regions in parallel and only fires alerts when the failure is confirmed across regions, cutting false positives without losing real-outage detection.
Broken visuals lose revenue quietly
A failed deployment that produces a blank checkout page, a third-party script that distorts the homepage, or a payment widget that silently fails to render can go unnoticed by basic uptime checks. Visual monitoring catches those changes automatically.
Alert fatigue kills monitoring tools
A monitor that pages you for every flake gets muted. Visual Sentinel uses cross-region confirmation, configurable retry counts, time-of-day rules, deduplication windows, and per-monitor alert routing so you only get woken up for real incidents.
The pipeline,
start to finish.
- Schedule.
Each monitor runs at the configured interval (60 seconds on Business+, configurable down to 5 minutes on lower tiers).
- Fetch.
Checks run from US and EU regions in parallel. A single-region failure does not fire an alert until cross-region confirmation completes.
- Evaluate.
Status code, response time, SSL chain validity, DNS records, full-page screenshot diff, content text diff. Each is compared against the per-monitor baseline.
- Persist.
Every check result is stored. Trends, baselines, and historical reporting all derive from this log.
- Alert.
A failed check that violates configured rules fires alerts to the routed channels. Duplicate alerts inside a configurable window are suppressed.
- Recover.
When the next check passes, the incident auto-resolves and a recovery notification fires on the same channels.
Try it without signing up.
One-shot checks against any URL or domain.
Website status checker
HTTP status, response time, server header, basic SSL state.
SSL certificate checker
Issuer, validity dates, SAN list, key algorithm, full chain.
DNS lookup
A, AAAA, MX, NS, TXT, CNAME, and SOA records for any domain.
Page speed test
TTFB, total load time, transfer size, redirect chain.
Three free monitors cover
most side projects.
Solo developers and indie hackers
Three free monitors with uptime and SSL checks cover a personal blog, portfolio, or side project. Catch breakage before your first users do.
Small businesses with one critical site
WhatsApp alerts when your storefront has a broken checkout. Visual regression catches Shopify theme bugs that pass uptime checks.
Agencies and consultancies
Monitor every client site with whitelabel status pages, per-client alert routing, and a single billing relationship at the Agency tier.