Dejal Systems (http://www.dejal.com/simon/) has announced Simon 4.0, an update to the server monitoring tool for Mac OS X.

Simon checks web pages, FTP and DNS servers, local or remote ports or volumes, and many other kinds of services for changes or failures. Version 4.0 includes a new design, unifying all of the lists, logs and editors into a single window. It also introduces groups, unlimited tests. email services, a context filter, filter output in the preview, password protection and more.

Dejal Simon 4.0 requires Mac OS X Yosemite. It's available for US$99; a demo is available for download. This is a paid upgrade for licensed Simon 3 users, with upgrades available for $49.