If you run a Squid proxy for an office, a lab, or a group of build servers, sooner or later someone asks why the internet is slow, and the honest answer is usually “let me check the logs”.
That check normally means running tail -f on /var/log/squid/access.log, squinting at Unix timestamps, and piping things through awk and sort until a pattern appears.
Tools such as SARG and Calamaris can turn Squid logs into reports, but they generate them in batches, so you only find out about a bandwidth hog after the damage is done.
What you really want is a view that updates while the traffic is happening, so you can see the busy client, the heavy domain, and the denied requests as they arrive.
GoAccess fills that gap, which is a fast, open-source log analyzer written in C that parses access logs incrementally and can push its results to a self-contained HTML report over a WebSocket.