XT (Xdebug Trace File)
The XT Developer file format
Xdebug, which is an Apache Web server plugin, generates output files with the extension XT. The plugin traces the execution of PHP code. The XT file saves all output of the PHP code in question in a line-by-line manner.
Technical details of XT files
The use of XT files is mainly debugging. With the help of these files, developers can check PHP functions for bugs, locate them and then proceed to fix them.