Universal SDR (universalsdr.com) is a free Windows app for software-defined radio receivers. Plug in an RTL-SDR, HackRF, LimeSDR or another SDR, click the waterfall to tune, and hear or decode the signals you are allowed to receive: FM and AM, aircraft (ADS-B, ACARS), ships (AIS), weather-satellite pictures, digital voice (DMR, D-STAR, YSF, NXDN, P25), pagers, amateur radio modes such as FT8, DAB+ digital radio and hundreds of 433 MHz sensors. It only receives unless you turn transmitting on. Early access is a free alpha program you join with an email address; from version 1.0 the free app will need no account.
Early access: join the free alpha program
The whole spectrum, made simple.