When running a SaaS, you can monitor everything. But should you? Alert fatigue is real. To keep your sanity and your uptime high, focus on these five critical metrics.

1. Uptime (Availability)

This is the baseline. If your service is down, nothing else matters. Aim for at least 99.9% uptime. Use an external monitoring tool like Pingbird to verify this from outside your network.

2. Response Time (Latency)

Slow is the new down. Amazon found that every 100ms of latency cost them 1% in sales. Monitor the response time of your critical API endpoints and landing pages.

3. Error Rate

What percentage of requests are failing? A sudden spike in 5xx errors is a sure sign of a bad deployment or a database issue. Set tight alerts on this.

4. SSL/TLS Expiry

It sounds trivial, but expired certificates cause embarrassing and costly outages every year. Automate this check so you never forget.

5. Core Web Vitals

Google uses these metrics (LCP, FID, CLS) to rank your site. Monitoring them ensures your SEO efforts aren't wasted by poor technical performance.

Conclusion: Start with these five. Once you have them under control, you can expand to more granular metrics. But never lose sight of the basics.