LoudParty is a small focused app — but each piece has weight. Here is what the build does, and why.
Up to eight iPhones (one host + seven listeners) play the same audio at the same instant. The host is the source of truth — listeners track its clock and buffer.
Free caps at three phones (1 + 2). Pro raises the ceiling to nine (1 + 8) — the technical ceiling of Apple's Multipeer mesh.
Every listener pings the host with an NTP-style round and locks to the host's audio clock. Playback is scheduled against the iOS audio engine — buffers are aligned at the sample, not the millisecond.
The offset is refined every 100 ms. End-to-end audible drift stays under 10 ms — below what the human ear can resolve as separate sources.
LoudParty runs entirely peer-to-peer over the local link — Apple's Multipeer Connectivity stack uses peer-to-peer Wi-Fi when the radios are on and falls back to Bluetooth otherwise. No router involved, no carrier, no cloud, no account. Listeners discover the host automatically — no pairing codes, no QR scans.
The full feature set works in airplane mode as long as Bluetooth (and ideally Wi-Fi) stays on. Beach, basement, motorway, plane — the app does not care.
LoudParty plays local audio files only — files you own and control. No streaming services, no rights snags, no "track unavailable in your region." If iOS can decode it, LoudParty can play it.
Bundled Milkdrop-era visualizers run locally on every device — spectrum bars, oscilloscope, plasma blobs, classic Milkdrop fields. Every listener renders the same frame at the same instant.
butterchurn-presets library — a handful of broken or visually noisy ones filtered outOnce the host is set, you barely need to open the app. Skip, pause, scrub, and switch tracks from the Lock Screen, Control Center, the Now Playing widget, or AirPods double-tap. The host stays in your pocket.
If you want to know exactly what is running on the device, here is the short version.
If you can't find an answer here, write to [email protected].
Not yet. LoudParty is an iOS app — the sync engine leans hard on iOS-specific audio APIs to hit sub-10 ms drift. A cross-platform version would be possible but would compromise on latency, which is the point of the app. For now: iOS only.
No. LoudParty plays local audio files you own — MP3, FLAC, AAC, WAV, etc. Streaming services don't allow third-party apps to redistribute their audio to other devices, and we'd rather have a clear "no" than a buggy "kind of." Bring your own files.
Pro caps at 9 (1 host + 8 listeners). That's the tested ceiling of the Bluetooth + Wi-Fi P2P mesh on current iPhones. Past 6, you may see one or two listeners drop and reconnect — the mesh degrades gracefully but it's not magic. For most rooms, 4–6 phones is the sweet spot.
The host runs a sustained audio session over a P2P mesh — that uses meaningful battery. Expect about 8% per hour on the host, 5% per hour on listeners. Plug in the host for parties longer than two hours. Listeners are fine on battery.
Yes, but under 10 ms — below the threshold of perception for the human ear at room distances. Stand a metre away from any two phones and you will hear them as one source. At very close range (phones touching) you can sometimes hear a faint chorus if the build is degraded; the app warns you.
LoudParty respects the iOS system volume and the Headphone Audio Levels safety feature. Eight phones at full volume in a small room get genuinely loud — use your judgement, and the per-device volume trim in Pro to balance.
No. The app makes zero network calls. No analytics, no telemetry, no crash reporting, no remote logging. We can't see who uses the app, how often, or what they play. The party stays in the room.
LoudParty is free for three phones. Unlock the full eight with Pro — $9.99 / year, cancel anytime.