Soundflower is a free system extension that lets you channel audio from one application to another . Perhaps you want to take the audio playing in a movie in your web browser and record it using QuickTime's audio input? Inter-application audio driver Soundflower can help you do this by emulating the interface of an audio device and allowing any audio application to send and receive audio with no other support needed.

Does Soundflower still work?

The Soundflower software was originally released in by Cycling '74 in 2004 and as an open-source project has encountered difficulties in keeping pace as Mac audio architecture has changed. Soundflower still works, however, despite the additional security steps required by Apple during installation.

Note that this download is for Mac OS X versions 10.5.8+.

Downloading and installing Soundflower

Users need to download and run the Soundflower Installer.pkg. The first time you run the installer (Soundflower.pkg), it will ask for your admin password and, depending on which Mac operating system you are using, this password might fail.

This is because kernel extensions on modern macOS versions now need to be given permissions before being loaded for the first time. The Soundflower installer will produce an error on macOS High Sierra, Mojave, and Catalina.

A security alert will appear and you will need to go to the Security and Privacy - General pane in System Preferences. Once there, there should be an Allow button that you can click to permit Soundflower (developer: MATT INGALLS) to open. Rerun the installer and, this time, the installation should be successful.

Installing Soundflower successfully was quite a challenging process, especially as there is no user instructions or tutorial to guide you through. We had to rely on researching the problem online and discovering the solution by ourselves.

Once installed successfully, the Soundflower extension runs with very low latency and CPU usage, allowing each client application to use its usual buffer size. This means it won't negatively impact your computer's performance.

What can I do with Soundflower?

There are many instances in which you might want to use Soundflower to channel audio between applications. Maybe you want to record the audio from a Skype or FaceTime interview, picking up both voices equally for more professional production. Or perhaps you'd like to record sounds from a frequency generation tool that's only available on the web?

Alternatively, you might need to do some creative re-sampling of a piece of audio by routing audio from apps such as iTunes and Spotify. Soundflower also allows users to record sound produced by their Macs such as audio channeled from outside sources like devices plugged into the USB and sound input ports.

Alternatives to Soundflower include iShowU, Audacity although neither work in exactly the same way.

Configuring and using Soundflower

Soundflower opens as one of two core audio devices (2ch/64ch). For most people and purposes, the 2-channel device is sufficient. The 64-channel device is provided for more complex routing situations and can be used with more than two applications simultaneously if the applications support audio routing to any channel.

To help users get started there are instructions in the Readme file found in the DMG download folder. These are, however, heavily focused on using Soundflower with Max/MSP, a visual programming language for music and multimedia. Users with more simple needs will have to look up instructions to configure Soundflower with more commonly used sound-capture apps.

To begin using Soundflower, open the Sound panel in System Preferences and you'll see Soundflower listed in the Output and Input tabs. Select the Output tab and choose Soundflower (2ch). Now, any sound that would normally come out of your Mac's speakers will be channeled through Soundflower.

It's important to remember this: if your Mac makes any sound — not only the audio you're trying to capture but also notifications and alerts — Soundflower will route that as well. Additionally, if you change your Mac's volume, that change will also be captured by the application that's recording Soundflower's audio.

Once you have selected Soundflower as the Output audio, you will need to configure the application you want to use to capture the audio. There are a couple of apps on your Mac that can record Soundflower's audio — QuickTime and GarageBand.

QuickTime is the easiest to configure; simply choose File and then select New Audio Recording. In the window that appears, click on the downward-pointing triangle that displays to the right of the Record button. Choose Soundflower (2ch) from the list that appears. When you're ready to begin capturing your chosen audio, just click Record.

One of the annoying things about Soundflower, however, is that when you choose it as your Mac's audio output, you can no longer hear the sound through attached speakers or headphones. You can avoid this issue by using alternative software such as Audio Highjack Pro or Audio Recorder.

Although we didn't have this issue when testing, some users experience interference when first setting up an audio channel. In this case, the user instructions recommend increasing the buffer size of both applications.