SonicSwarm: Sound Connect

Turn any group of phones into one giant speaker.
Nobody brought a Bluetooth speaker? No problem. SonicSwarm turns the phones already in everyone's pockets into one synchronized sound system. Host a swarm, have friends join, hit play — every connected phone plays the same audio at the exact same moment. Spread the devices around the room and the combined sound fills the space.
No accounts. No sign-up. No cloud servers. Everything syncs directly between the phones on your Wi-Fi network.
HOW IT WORKS
One person taps "Host a Swarm" and picks what to play. Everyone else taps "Join a Swarm" and connects automatically over the local network. When the host presses Play, every phone starts playing together using a peer-to-peer clock-sync algorithm built specifically for this — no cloud round-trip, no buffering delay, just phones talking directly to each other.
PLAY YOUR OWN FILES
Import any audio file already on your device — from the Files app, iCloud Drive, AirDrop, wherever. This is SonicSwarm's tightest sync mode: the host sends the file to every connected phone, and playback is scheduled using hardware-level timestamps for very close alignment across devices. Previously imported tracks are saved automatically, so you can reuse them instantly next time without digging through Files again.
PLAY FROM SPOTIFY
Have a Spotify Premium account? Copy a track link from the Spotify app and paste it into SonicSwarm — it plays across every connected phone that also has Spotify installed. A convenient way to play anything in Spotify's catalog without needing the file itself.
WHO IT'S FOR
Backyard hangouts and campsite gatherings where nobody packed a real speaker
Dorm rooms and small get-togethers
Anywhere a single phone speaker just isn't loud enough, but a real speaker isn't around
WHAT MAKES IT DIFFERENT
Most multi-device audio comes with a subscription. SonicSwarm doesn't gate the core feature behind a paywall or a monthly fee — host and join freely, using audio you already own.
Under the hood, SonicSwarm doesn't just tell every phone to "hit play at the same time" and hope for the best. It actively measures the clock offset between every connected device using a lightweight, continuous ping exchange, then schedules playback using each phone's own hardware audio clock — the same category of technique used in professional audio synchronization, built for a phone in your pocket.
GOOD TO KNOW
All devices need to be on the same Wi-Fi network (or close enough for a Bluetooth fallback)
Spotify playback requires Spotify Premium and the Spotify app installed on every phone in the swarm, not just the host — sync quality for Spotify is close but not sample-accurate, since playback runs through Spotify's own app rather than SonicSwarm directly
Import Track offers the tightest, most precise sync of the two playback modes
Works best with a handful of devices in one room — very large groups (10+ phones) may see slower connection and file-transfer times