XTide uses less than 15 MB of memory for a typical interactive session. The base configuration for which XTide 2 was written was a 166 MHz Pentium PC with 32 MiB of RAM (circa 1997). XTide continues to be runnable on such a PC and on comparable non-PC hardware such as a Sun Sparcstation. Unfortunately, to build XTide comfortably with GCC now requires much more memory.
XTide is Unix software. It is intended to compile and run correctly on any reasonably modern version of Unix. However, I no longer have direct access to any flavor of Unix other than Linux, so I can only make portability fixes if and when issues are reported.
In order for tide predictions to have the correct Daylight Savings Time (Summer Time) adjustments, your platform must provide a sufficiently up-to-date version of the tz database. If your time zone database is obsolete, you may be able to upgrade it using the latest version from https://www.iana.org/time-zones or by installing an operating system patch.
Some non-Unix platforms have limited support as detailed in the ports section. The command-line client tide and the backend library libxtide are easily built in most any command-line environment with a good C++ compiler.
XTide is written in C++. The compiler is expected to support C++11 features by default. GCC version 6.1 or newer should work.
A list of libraries on which XTide is dependent is provided in the next section.
You might need an archive utility like xz or 7-Zip to uncompress files.