SDR#, also written SDRSharp, is the radio receiver software from Airspy, a maker of software-defined radio hardware. It runs on Windows only and is a free download from airspy.com. Unlike Gqrx or GNU Radio, it is not open source: its source code is not published, and the official documentation describes it as freeware, meaning the program costs nothing but remains under the publisher’s control.
The program is the work of developer Youssef Touil, who is credited in the official SDRSharp Big Book guide. The same guide includes a screenshot dated April 2012, which places its beginnings at least that far back. The current revision is number 1921, dated January 1, 2025, with revision 1922 available as a beta.
What SDR# (SDRSharp) is for
SDR# takes the sample stream from an SDR receiver, draws it as a spectrum and a waterfall, and demodulates the slice of the band you select. It covers the usual listening modes, AM, narrow and wide FM, single sideband and CW, along with tools to measure signal levels. It is designed first for Airspy’s own receivers, the R2, Mini, HF+ Discovery and HF+ Dual Port, with which it is closely integrated. The main package also bundles drivers for the HackRF, RFSPACE network receivers and AOR receivers, plus a setup script for RTL-SDR dongles.
Much of its reputation comes from its audio processing and its plugin system. The changelog published by Airspy shows steady work on its NINR noise reduction, and the official guide describes a co-channel canceller that helps when two transmitters overlap on the same frequency. Plugins go into a Plugins folder and load at startup. Airspy provides a development kit for writing them, and a community plugin package maintained by Rodrig Pérez, linked from the download page, gathers many of them in one installer.
SDR# also works as a client for SpyServer, Airspy’s server software that shares a receiver over the network, so a receiver installed on a rooftop or at a remote site can be used from several computers. Under the hood it runs on Microsoft’s .NET platform, which Airspy has upgraded over time, from .NET 6 in late 2021 to .NET 8 today, according to the changelog.
Comparing it with Gqrx, which we also cover, is useful. On screen the experience is similar, but Gqrx is free software that runs on Linux, macOS and Windows, while SDR# is closed and Windows-only, in exchange for a larger plugin catalog and finer control over Airspy hardware. GNU Radio belongs to a different category altogether: tools for building your own signal processing.
Who is it for?
SDR# is aimed at listeners and radio amateurs with a Windows PC, above all owners of an Airspy receiver, who get the most out of it. It is also widely used with RTL-SDR dongles, and documentation is plentiful: the SDRSharp Big Book, a free user guide, is available in several languages, including French and Italian, on the Airspy website.
There is no version for Linux or macOS, where Gqrx is the obvious alternative. Because the code is closed, you cannot audit or adapt it. The sheer number of settings can be confusing at first, and the download page warns that some older plugins do not work with the 64-bit build. No new revision has been released since January 2025 as of this writing. As with any receiver, listening to certain communications is regulated in many countries.
Download SDR# (SDRSharp) safely
The only official source is the download page on airspy.com. The main 32-bit package contains SDR# and drivers for the supported hardware. A 64-bit production build, faster on recent computers, and two beta builds are offered alongside it, together with the plugin development kit. The software comes as an archive: the official guide recommends extracting it to a folder outside Program Files and running SDRSharp.exe, with nothing written to the registry.
SDR# is free, with no subscription and no paid features. Since its code is not public, only Airspy’s own archives can be trusted: a copy hosted on a generic download site may be outdated or altered, and there is no way to check. The community plugin package by Rodrig Pérez, for its part, is linked directly from airspy.com.
Frequently asked questions
Is SDR# open source?
No. SDR# is free of charge, but Airspy does not publish its source code, and its documentation calls it freeware. If free software matters to you, Gqrx is the natural choice for listening and GNU Radio for experimenting.
Does SDR# work with an RTL-SDR dongle?
Yes. The main package includes a script that installs the driver RTL-SDR dongles need. Its most advanced features, however, are designed around Airspy receivers, where the software is at its best.
Can I use SDR# on Linux or a Mac?
No, Airspy only releases it for Windows. The company does offer SpyServer for Linux, so you can connect the receiver to a Linux machine and listen remotely from SDR# on a Windows PC.
