The gap: your Mac will not record its own output
Search for how to record system audio on Mac and you run into a strange gap. Out of the box, a Mac gives you no simple way to record the sound it is playing: QuickTime will record your screen and your microphone, but the system's own output, the audio actually coming from the speakers, is not on offer.
People hit this constantly. You want to capture a live stream that will not exist tomorrow, save the audio from an app with no export button, or record the output of a web instrument. The usual fix is installing a loopback audio driver. That still works, and we cover it below, but there is now an easier route, and it lives in your browser.
The browser trick: Entire Screen plus Share system audio
Chrome and Edge can capture tab or system audio through the same picker they use for screen sharing. We built our free Audio Screen Recorder on top of that. It records computer, tab, app, or system audio straight to a WAV file, and it runs in the browser: nothing uploaded, we never see the file.
Here is the whole process. Open the tool in Chrome or Edge and hit record; the browser opens its screen-share picker. Select Entire Screen, tick the Share system audio toggle, and confirm. Play whatever you want to capture, stop when you are done, and save the WAV. No driver, no install, no account.
The Entire Screen choice is the non-obvious part. On macOS, the Share system audio toggle only appears when you share the whole screen, not a single window. You are sharing the screen purely so the browser will hand over the audio; the tool keeps the sound and writes it to WAV.
Honest caveats before you rely on it
A few plain caveats. Safari support for this kind of capture is weak, so use Chrome or Edge. Recording happens in real time, meaning a 30-minute capture takes 30 minutes. And system audio means all of it: message pings and calendar alerts land in your recording, so silence notifications before you start.
macOS will also ask you to allow the browser to record the screen. That is a normal system permission prompt, not something specific to our tool. If the Share system audio toggle never shows up, check that you picked Entire Screen rather than a window. And the capture is only as good as the source: the recorder writes exactly what the Mac plays, so a low-quality stream stays low quality.
If you only need the sound from one tab, select that tab in the picker and share its audio instead, which keeps stray sounds from other apps out of the capture. One plain note on rights: recording something for personal reference is one thing, but publishing audio you do not own generally needs permission from the rights holders.
When you need more: the BlackHole driver route
The browser trick covers occasional captures well. If you record system audio every day, or you need it showing up as an input inside a DAW, a loopback driver is the deeper fix. BlackHole is a well-known free option on macOS: you install it as an audio driver, route the Mac's output through it, and it appears as an input that any recording app can capture.
The trade-offs are real. You are installing a system audio driver, and you will need to set up routing so you can still hear what you are recording. None of that is hard, but it is setup, and it stays on your machine long after the one recording you needed. Our rule of thumb: browser first, driver when the browser route stops being enough.
Sharing the recording: from WAV to something smaller
The recorder saves WAV because it is safe: uncompressed PCM, an exact copy of what was captured. The cost is size, roughly 10 MB per minute at CD quality, so an hour of capture lands around 600 MB. That is fine on your drive and terrible in an email.
For sharing, convert a copy to MP3. At 320 kbps, MP3 is near-transparent for most listeners, and the file drops to roughly a quarter of the WAV's size. Our free Audio Converter handles this with FFmpeg running in WebAssembly and a bitrate picker from 128 to 320 kbps, and there is a dedicated WAV to MP3 page if that is the only trip you need. It also handles M4A, FLAC, OGG, and AIFF if MP3 is not the target. Same deal as the recorder: it runs in the browser, nothing uploaded, we never see the file.
Keep the original WAV. Converting a lossy MP3 back to WAV later will not restore anything, so the WAV is your master and the MP3 is the copy you send. If you want the longer version of that trade-off, we wrote up WAV vs MP3 separately.
The short version
Open the recorder in Chrome or Edge, pick Entire Screen, tick Share system audio, and you get a clean WAV with nothing installed. Reach for BlackHole when you need system audio as a permanent input. Convert a copy to MP3 when it is time to share.
That covers the capture side. If what you are capturing is raw material for music, we also make XportStudio, a free desktop app for singers and producers; you can grab it here. Either way, the browser tools stay free.