Nagios is the grand father of open source monitoring solutions and has an impressive track record that spans from 1999 until today.
Opsdis is a proud Nagios partner since 2018 and have worked with Nagios since the early days.
Today Nagios comes in two flavours, Nagios Core that is 100% open source and Nagios XI which is a commercial ready to use product.
If you have an existing Nagios installation or if you’re curious about Nagios XI we can help.