Now that you have a VPS up and running smoothly, you want to keep in that way—or, at the very least, know if something goes wrong. Luckily, a huge variety of monitoring solutions exist to help give you a head’s up if an entire server crashes, a webapp is taking too long to respond, or you’re hitting your CPU limits.

Now, there are some truly excellent enterprise-level monitoring suites out there, if that’s of interest to you. We called out New Relic in the headline, as it’s one of the most popular monitoring solutions out there, but the competition is fierce, with other players like Pingdom, Twilio, and Stackify trying to get some of the monitoring marketshare. But even though many of these solutions have a free tier, we think it’s possible to get much of the same functionality without being boxed into a SaaS application.

With that said, we’re going to focus on open source, self-hosted alternatives that don’t cost you a penny.

It should be noted that not all of these applications perform the same function, or include the same features, so don’t think of this list as a side-by-side comparison between any of these 7 applications, or any of the other ones mentioned above.

Here’s some of our favorites.