Open Server is not available for Mac but there are some alternatives that runs on macOS with similar functionality. The best Mac alternative is XAMPP, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to Open Server and nine of them are available for Mac so hopefully you can find a suitable replacement. Other interesting Mac alternatives to Open Server are MAMP (Freemium), AMPPS (Free), Devilbox (Free, Open Source) and Fenix Web Server (Free, Open Source).
XAMPP is a completely free, easy to install Apache distribution containing MariaDB, PHP, and Perl. The XAMPP open source package has been set up to be incredibly easy to install and to use. XAMPP is free even for commercial uses
MAMP installs a local server environment in a matter of seconds on your computer. It comes free of charge, and is easily installed. MAMP will not compromise any existing Apache installation already running on your system.
Zend Server is the #1 professional PHP stack. It is the most complete PHP distribution with a continuously updated set of advanced value-add features designed to optimize productivity, performance, scalability and reliability.