A software system is disclosed which facilitates the process of tracing the execution paths of a program, called the client. The tracing is performed without requiring modifications to the executable or source code files of the client. Trace data collected during the tracing operation is collected according to instructions in a trace options file. At run time, the tracing library attaches to the memory image of the client. The tracing library is configured to monitor execution of the client and to collect trace data, based on selections in the trace options file. The developer then uses a trace analyzer program, also having a graphical user interface, to view the trace information. The system can trace multiple threads and multiple processes. The tracing library is preferably configured to runs in the same process memory space as the client thereby tracing the execution of the client program without the need for context switches. The tracing system provides a remote mode and an online mode. In remote mode, the developer sends the trace control information to a remote user site together with a small executable image called the agent that enables a remote customer, to generate a trace file that represents execution of the client application at the remote site. In online mode, the developer can generate trace options, run and trace the client, and display the trace results in near real-time on the display screen during execution of the client program.