5 Nginx Log Patterns Every SaaS Developer Should Monitor

Most SaaS applications run behind Nginx, and most teams only look at their logs when something breaks. That is a mistake. Your access logs are a real-time feed of what is happening to your application — including attacks, abuse, and infrastructure problems — if you know what to look for. Here are five patterns worth monitoring continuously. 1. Repeated 401/403 Responses to the Same Endpoint A spike in 401 Unauthorized or 403 Forbidden responses targeting a single endpoint — especially /api/login , /admin , or /api/token — is a strong indicator of brute force or credential stuffing activity. awk '$9 == "401" || $9 == "403" {print $7}' /var/log/nginx/access.log \ | sort | uniq -c | sort -rn | head -20 If you see hundreds of hits on /api/login returning 401, an automated attack is almost certainly in progress. Combine with IP analysis: awk '$9 == "401" {print $1}' /var/log/nginx/access.log \ | sort | uniq -c | sort -rn | head -20 A single IP hammering your login endpoint warrants an immed