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What is Uptime Monitoring?
Uptime monitoring checks whether your websites, APIs, and services are accessible and responding correctly. When something goes down, you get alerted immediately.
How It Works
An uptime monitoring service regularly sends requests to your endpoints and checks the response:
- HTTP checks — Sends a request, expects a 2xx status code
- Response time — Measures how long the response takes
- Content validation — Optionally checks for specific content in the response
- SSL verification — Confirms your HTTPS certificate is valid
If a check fails (no response, error code, timeout), the service verifies with a second check to avoid false alarms, then alerts you.
Why It Matters
The cost of downtime:
- Lost revenue from failed transactions
- Damaged reputation and customer trust
- SEO penalties for unreliable sites
- SLA violations and potential refunds
The longer an outage goes unnoticed, the worse the impact. With monitoring, you know in minutes, not hours.
What to Monitor
- Public website — Your homepage and key landing pages
- API endpoints — Health checks and critical API routes
- Web application — Login pages, dashboards, checkout flows
- Third-party services — Payment providers, auth services, CDNs
Key Metrics
Uptime Percentage
How often your service is available. 99.9% uptime = ~8.7 hours of downtime per year.
Response Time
How fast your service responds. Slowdowns often precede outages.
Time to Detect (TTD)
How quickly issues are identified. With 1-minute checks, TTD is under 2 minutes.
Best Practices
- Monitor from outside your infrastructure (use an external service)
- Check frequently (1-5 minute intervals)
- Set up multiple alert channels (email + Slack)
- Monitor critical dependencies, not just your own services
- Test your alerts regularly to make sure they work