Cue01
Game audio
Your game is never touched.
Sidestage captures only the apps you pick. Your game is never captured, routed or processed, so footsteps and gunshots keep their exact position and timing.
Free forever
Open source · MIT OR Apache-2.0
Your game, centre stage. Everything else in the wings.
Sidestage plays the apps you choose, like Spotify, a podcast or Discord, in 3D around your head on headphones. Your game's audio is never captured or processed, so footsteps and gunshots keep their exact position and timing.
Coming nextUp to 8 apps at once, each in its own spot, arrives in the next update. Version 0.1 places one app.
01 · Hear it in your browser
Move the music. The footsteps stay put.
Press play: a lo-fi loop comes from the violet puck and a friend murmurs from the coral one. Drag them anywhere around your head. The game's footsteps cross in front of you and skip the 3D stage completely, the same way your real game skips Sidestage.
Drag a puck, or click the radar to move the selected one (Ctrl snaps to 15°). Keyboard: focus a puck, then use the arrow keys (Shift for small steps), Page Up and Page Down for height, Home to reset.
Use headphones. Binaural 3D doesn't work on speakers.
This browser can't play Web Audio, so the sound check stays silent here. The radar still moves.
Music position
Behind you · 1.5 m
60° wide · height 0°
On stage
Sound
An honest note: everything here is synthesized on this page and placed with your browser's generic HRTF, not Sidestage's own renderer, and generic HRTFs often blur front and back. Treat it as a sketch of the idea; the app itself sounds different.
02 · The cue sheet
Everything that isn't the game, handled in the wings.
In a theatre, the cue sheet lists what happens offstage so the show runs clean. Here is Sidestage's.
Cue02
The radar
Drag a sound anywhere around your head.
Direction, distance from 0.5 to 20 m on a log scale (or the scroll wheel), and height with Shift-drag. Ctrl snaps to 15°, a double-click goes back to the preset, and the arrow keys work too. Or start from one of six presets.
Cue03
Footstep-safe
Music stays out of the footstep band.
One switch cuts the music by at least 6 dB around 3.2 kHz, where footsteps live, rolls off the highs, lowers the bass and makes ducking competitive. The cues you play by stay clear.
Cue04
Ducking
Music steps back when the game gets loud.
Sidestage listens to everything except the music to decide. Choose how hard: Off, Gentle, Standard or Competitive.
Cue05
No double audio
You never hear an app twice.
The app's normal sound is hidden automatically while Sidestage plays it in 3D. If Sidestage is killed, your audio comes back: a helper process restores it on Windows and Linux, and macOS does it by itself. sidestage restore is there if you ever need it.
Cue06
Privacy
Nothing leaves your machine.
There is no network code in Sidestage at all. No telemetry, no accounts, no update checks. Audio is processed in memory and never recorded.
NextNew07
New · coming nextNew
Up to 8 sources at once, and voices at your side.
Each source gets its own spot, colour, preset, volume and ducking. Voice presets tuned for Discord come with Clarity and a Leveler that evens out loud and quiet friends: a talker 12 dB quieter comes out within about 4 dB. Voice chat is never turned down for the game; your music and podcasts turn down while someone talks instead. A "Never duck for these apps" list keeps sounds like a video in your browser from turning your sources down, and a limiter keeps several loud sources from clipping.
03 · On real hardware
Spotify behind you. Valorant exactly as it was.
Version 0.1 was tested on Windows 11 with Spotify spatialized while playing Valorant, and 0.2's multi-source engine passed its live tests on real hardware with test tones. Both of these show the real app, not a mock-up.
- Windows 11: tested on real hardware.
- Several real apps at once: the engine passed its live tests with test tones, but several real apps together haven't been tried yet.
- macOS 14.2+ and Linux: build and pass CI, not yet tried on real machines.
Coming nextNewProduction stills
Three sources, voice presets, a never-duck list.
In demo mode, with simulated apps: Spotify behind you, Pocket Casts on your left, Discord on your right.
-
Up to 8 sources at onceEach with its own place on the radar, its own colour and its own preset. -
Voice presets for DiscordLevelled, clarified, never ducked for the game. -
Turn down while voice chat talksAnd a never-duck list for apps that shouldn't count as the game. -
Add a sourceClick an app to add it; it gets a preset that suits it. -
A crowd around youFour sources, all clear of the game's wedge in front of you.
04 · Download
Free forever. Bring headphones.
No price, no account, no telemetry. Pick your system; every button goes to the latest release on GitHub. Upgrading from 0.1 keeps your settings: they become your first source.
Windows
TestedWindows 11 · Windows 10 2004+ may work
Tested on real hardware, with Spotify spatialized while playing Valorant. Unzip and run sidestage.exe.
Tested on real hardware: 0.1 with Spotify while playing Valorant, and 0.2's multi-source engine with live test tones. Unzip and run sidestage.exe.
Not code-signed yet, so SmartScreen warns you the first time: choose More info, then Run anyway.
Download for WindowsmacOS
ExperimentalmacOS 14.2 or later · Apple silicon and Intel
Builds and passes its tests in CI, but hasn't been tried on a real Mac yet.
Not notarized yet: open it once, then allow it in System Settings, Privacy & Security. Reports are very welcome.
Download for macOSLinux
Experimentalx86_64 · PipeWire or PulseAudio
Builds and passes its tests in CI, but hasn't been tried on a real desktop yet.
If it runs (or doesn't) on your distro, an issue on GitHub helps a lot.
Download for LinuxHeadphones required: binaural 3D doesn't work on speakers. Open source under MIT OR Apache-2.0. Read the code
05 · Questions
Before the curtain goes up.
Or build it yourself with Rust 1.95 or newer:
$cargo run --releaseDoes it work on speakers?
No. Sidestage renders binaural audio, which needs one channel per ear. On speakers the 3D effect falls apart.
How many apps can it place at once?
Version 0.1 places one. The next update places up to 8 at once, each with its own position and preset, plus voice presets for Discord.
Up to 8 at once, each with its own position and preset. Voice chat gets its own presets, tuned for Discord.
Does Sidestage touch my game?
Never. It captures only the apps you choose. The game's audio is not captured, routed or processed, so its footsteps and gunshots keep their exact position and timing.
Why does the Windows Volume mixer show my apps at 0?
That is how the originals are hidden on Windows: each source's app is turned down to -120 dB and its captured copy is boosted back by the same amount. Use Sidestage's own volume sliders instead. If Sidestage is killed, a helper process puts the volumes back right away.
The music sounds in front of me, not behind.
Generic head models sometimes confuse front and back. Moving the music a little to one side, or adding distance and room, helps. On Windows, also turn off spatial sound (Windows Sonic, Dolby Atmos or DTS) for your headphones.
My Bluetooth headset loses the effect.
A headset in hands-free (microphone) mode switches to low-quality mono, which can't carry 3D audio. Use its stereo mode. On Windows, Sidestage warns you about this.
What does it keep on my computer?
Only its settings, its logs and small crash-recovery journals that record which app volumes or routes to put back. Audio is processed in memory and never saved, and nothing is sent anywhere.