.NET Relayer is a program for quick relay algorithm simulation and testing. It is also a powerful IEEE COMTRADE file viewer. With a user interface that is streamlined to help users obtain results quickly, .NET Relayer allows users to write their own relay algorithms. After compilation, these algorithms can be instantly tested against prerecorded waveforms in the COMTRADE format. For the first time, relay algorithms can be written in C# or Visual Basic and be integrated into the standard relay simulation and testing process. Relay algorithms may be integrated into functional libraries. Relay algorithms may also interface with and take advantage of functions already written in C, FORTRAN, Pascal, etc. or functions present in native libraries (DLLs). All relay functions may output a set of results for subsequent analyses. Relay functions may also generate events. All relay events are recorded and can be transfered to a printable analysis report. The .NET Relayer program includes a comprehensive and interactive grid and graphical display of waveform data. Waveform data can be copied to spreadsheet applications for additional processing. Graphical waveform displays provide visual insights of the recorded waveforms and can be exported to other applications. Other features include an easy way to setup relay protection zones in trajectory plots and a transparent integration of user functions into relay simulations. Examples of waveform files, relay functions, and waveform generators are also distributed with the software. Beyond relay simulation and testing, the .NET Relayer software is a tool to graphically inspect mathematical expressions and is also suitable for general waveform analysis.