Harmonics, especially the 3^rd,5^th, and 7^th components, are significant disturbances in power systems, occurring simultaneously and at varying time intervals. Measurements of these components depend on factors such as fundamental frequency deviation, event duration, amplitude values, and noise levels. Accurate detection and measurement are crucial for effective harmonic mitigation and preventive strategies. This study introduces a harmonic signal analysis application utilizing methods like FFT, STFT, CWT, EMD, and HHT, with individual user interfaces for in-phase and time-variant harmonic signals. The application provides results for amplitude, frequency, event time intervals, and noise effects simultaneously. Test results at a 60 dB signal-to-noise ratio (SNR) reveal that FFT achieves precise frequency and amplitude results due to its high resolution, whereas other methods offering time-frequency domain results exhibit lower resolution. EMD, in particular, demonstrates high errors in frequency and amplitude responses, reducing four frequency components to three. HHT, utilizing EMD results, yields higher accuracy with minimal errors compared to other methods. This application, combined with test results, facilitates signal synthesis and comparative analysis in time and time-frequency domains.