Despite it being hard to install if you're not really familiar with PHP
It's a fairly (conceptually) simple app. It ingests your web server logs, puts some representation of them in a MySQL database, and provides a web app that presents an analysis of those logs.
When I first started looking for non-Google-Analytics traffic statistics software, I thought I didn't need any analysis and tried the venerable awstats
. Well, I could not tell what was going on with that, and I especially couldn't tell crawler traffic apart from probable human visits.
Matomo (formerly called Piwik) gives you that information in a UI that's like Google Analytics before it tried to take on way too much.
And of course, most importantly, you get this information without providing Google with more eyes on the behavior of people that are just visiting your web site
and didn't actually consent to being tracked by Google.
The thing that I am especially pleased with is that Matomo lets you avoid having to have extra JS on pages, which requires more bandwidth and more trust from your users. It can just read your server logs, which has all the information needed to figure out what's being visited, and what kind of traffic it is.
Already, I see a ton of traffic from crawlers and bots I know nothing about (though some of them are blatantly malicious). Of course, now I have to set about evaluating and blocking them, which is work, but it's better than the alternative.