A homepage can return 200 OK while login fails, checkout serves a JavaScript error, a background job stalls, or one region cannot resolve the domain. A full-stack website monitoring checklist maps each customer-visible capability to the signal that can disprove it is healthy.
This guide is a coverage inventory: what layers and failure modes to observe. If your immediate goal is ownership, escalation, and incident readiness, use the separate pre-outage monitoring checklist.
1. Public Reachability
Yes, start with the basics.
Your homepage is usually the first thing users hit. If it's down, nothing else matters.
What to check:
- HTTP status code returns 200
- Response time stays within the endpoint's defined service objective
- Check frequency supports the service's detection objective
Why it matters: If your homepage is down for 10 minutes and you don't know, that's 10 minutes of lost visitors, signups, and trust.
2. Critical User Flows
Your homepage might be up, but is your signup form working? Is your checkout process functional?
What to monitor:
- Login page
- Signup/registration flow
- Checkout or payment pages
- Dashboard or main app entry point
Pro tip: Create a dedicated health endpoint for each critical flow that actually tests the underlying functionality, not just serves a static page.
3. API Endpoints
If your product has an API (or is an API), you need dedicated endpoint monitoring.
What to check:
- Response status codes (200, 201, etc.)
- Response time thresholds
- Response body validation (optional but powerful)
- Authentication still working
Common blind spots:
- Background job endpoints
- Webhook receivers
- Third-party API integrations
APIs fail silently all the time. Don't let yours be one of them.
4. SSL Certificate Expiration
Certificate expiration is preventable when renewal and expiry alerts are both tested.
When your SSL certificate expires:
- Browsers show scary security warnings
- Users can't access your site
- Google may temporarily de-index pages
- Trust evaporates instantly
What to monitor:
- Days until expiration (alert at 30, 14, and 7 days)
- Certificate chain validity
- Certificate issuer and renewal status
Best practice: Set up automated alerts well in advance. SSL renewal should never be a surprise.
5. Domain Expiration
Similar to SSL, but even more catastrophic when it fails.
What happens if your domain expires:
- Complete site inaccessibility
- Potential domain squatting by third parties
- Email delivery failures
- Massive SEO damage
What to monitor:
- Days until domain expiration
- Registrar lock status
- DNS configuration changes
Set alerts for 90, 60, 30, and 7 days before expiration.
6. Response Time / Performance
Your site might be "up" but unusably slow.
Slow websites can frustrate users, reduce conversion, and precede capacity-related outages. Use your own historical latency and business metrics instead of a universal conversion-loss claim.
What to track:
- Time to First Byte (TTFB)
- Full page load time
- API response latency
- Response time degradation over time
Define warning and critical thresholds from baseline percentiles and user impact. A static page, an API request, and a browser checkout need different limits; see latency percentiles explained.
7. Error Rates and Status Codes
HTTP 200 is great. But what about the 500s, 502s, and 503s happening on other pages?
What to monitor:
- 5xx error rates (server errors)
- 4xx error rates (client errors, especially 404s)
- Error spikes vs. baseline
Why this matters: A single broken endpoint throwing 500 errors might not bring down your whole site — but it could break a critical feature your users depend on.
8. Database Connectivity
Many outages are database-related:
- Connection pool exhaustion
- Replica lag
- Query timeouts
- Disk space running out
What to monitor:
- Database connection success
- Query response times
- Connection count and pool health
- Storage utilization
Tip: Create a simple /health endpoint that performs a basic database read/write operation. Monitor that endpoint for true application health.
9. Third-Party Services
Your site depends on services you don't control:
- Payment processors (Stripe, PayPal)
- Email providers (SendGrid, Mailgun)
- CDN (Cloudflare, Fastly)
- Authentication (Auth0, Firebase)
- Analytics (Google, Segment)
What to do:
- Monitor their status pages
- Track their response times from your end
- Have fallback plans for critical services
When Stripe goes down, your checkout goes down. Know about it instantly.
10. Multi-Region Availability
Users don't all come from one place.
Your site might be fast in Europe but slow in Asia. It might be up from your office but down for California users.
What to monitor:
- Latency from multiple geographic regions
- Regional outages (CDN issues, routing problems)
- DNS resolution times globally
Why it matters: A regional outage can affect thousands of users while your local tests show everything as "green."
Bonus: Monitor Your Monitoring
Here's an often-overlooked point:
Who's watching the watchers?
Make sure your monitoring system itself is reliable:
- Use a monitoring provider with high uptime SLA
- Set up redundant notification channels (email + SMS + Slack)
- Test that alerts actually reach you periodically
The Complete Checklist Summary
Here's your quick-reference checklist:
| What to Monitor | Alert Threshold | Check Frequency |
|---|---|---|
| Homepage uptime | Unexpected status, content, or timeout | Detection objective |
| Critical user flows | Business outcome assertion fails | Journey objective |
| API endpoints | Contract, status, or latency fails | Endpoint objective |
| SSL certificate | <30 days expiry | Daily |
| Domain expiration | <90 days expiry | Weekly |
| Response time | >3 seconds | Every 1-5 min |
| Error rates | Spike above baseline | Continuous |
| Database health | Connection failure | Every 1-5 min |
| Third-party services | Degraded/down | Every 5 min |
| Multi-region | Regional failures | Every 5 min |
How to Avoid Alert Fatigue
A checklist this comprehensive sounds like a recipe for notification overload.
Here's how to stay sane:
- Set appropriate thresholds — Not every blip is an emergency
- Use escalation policies — SMS for critical, email for warnings
- Group related alerts — Don't get 10 notifications for the same root cause
- Schedule downtime windows — Silence alerts during planned maintenance
- Review and tune regularly — Adjust thresholds based on real patterns
The goal is actionable alerts, not noise.
Getting Started Is Easy
You don't need to implement all 10 checks on day one.
Start with these three:
- Homepage uptime
- SSL certificate monitoring
- One critical API endpoint
Then expand as you go.
Most monitoring tools (including Webalert) let you set up these checks in seconds — and scale from there.
If you want to see what’s included, check the full Webalert features and compare plans on pricing.
Final Thoughts
"Is my site up?" is a great starting question.
But true reliability means asking:
- Is it fast?
- Is it secure?
- Is it working for all users?
- Will it still be working next month?
This checklist helps you answer all of those questions — and catch problems before your users do.
Ready to monitor your full stack?
Start monitoring for free with Webalert — uptime, SSL, response time, and more in one simple dashboard.