SDR++

SDR++ is a lightweight, fast receiver program for software-defined radio, with SIMD-accelerated signal processing. You connect a receiver such as RTL-SDR, HackRF, Airspy, SDRplay, LimeSDR or PlutoSDR, view a continuous spectrum and waterfall, demodulate several channels in parallel with multiple VFOs, and record a signal or audio. It has a modular design with plugins and a server mode for running a remote receiver. RF engineers and students use it to scan frequencies, track down interference and test transmitters and wireless modules. Limitation: it is a receiving and analysis tool, not a circuit design tool, and on some distributions you should use the official builds rather than the repository package.