There is no specific "AJAX server" that is included with a Mac, as AJAX (Asynchronous JavaScript and XML) is a client-side technology used for making asynchronous requests to a server.
However, a Mac can be used as a web server to serve the files needed for an AJAX application. Macs come with a built-in web server, Apache, which can be used to serve web pages and files, including those required for an AJAX application. To enable Apache on a Mac, you can open the Terminal app and type `sudo apachectl start`. This will start the Apache web server and allow you to serve files from the default web root directory `/Library/WebServer/Documents/` or any other directory you choose to configure.
You can then use a text editor or an integrated development environment (IDE) to create your AJAX application, and serve the files through Apache on your Mac. Once the files are served, you can access the application through a web browser on the same Mac or on a different device connected to the same network.