GNU Radio is described as 'Free & open-source software development toolkit that provides signal processing blocks to implement software radios. It can be used with readily-available low-cost external RF hardware to create software-defined radios, or without hardware in a simulation-like' and is an app in the development category. There are more than 10 alternatives to GNU Radio for a variety of platforms, including Linux, Mac, Windows, Android and BSD apps. The best GNU Radio alternative is Gqrx, which is both free and Open Source. Other great apps like GNU Radio are Simulink, Universal Radio Hacker, SigDigger and SDR#.
LuaRadio is a lightweight, embeddable flow graph signal processing framework for software-defined radio. It provides a suite of source, sink, and processing blocks, with a simple API for defining flow graphs, running flow graphs, creating blocks, and creating data types.
SoapySDR is an open-source generalized C/C++ API and runtime library for interfacing with SDR devices. With SoapySDR, you can instantiate, configure, and stream with an SDR device in a variety of environments. Both osmosdr and uhd devices are available within SoapySDR.
Multi Physical Nexus is a new software that allows the user to create visual diagram and print charts or export data in files. It is already well working, but it is still under developpement and does not include all the simulink features.
Advanced features, reduced layers of abstraction on LimeSDR