A native iOS synthesizer with lush shimmer reverb. Connect wirelessly via Bluetooth LE or wired via USB-C and play 28 hand-crafted presets across Pads, Keys, Strings, Brass and Synth — at ultra-low latency.
⬇︎ Download on the App StoreBuilt with AVAudioEngine and CoreMIDI — no external libraries, no latency. Two tabs: Synth for playing, Chords for real-time chord analysis.
Connect wirelessly to any BLE MIDI adapter (e.g. Yamaha MD-BT01). Tap the Bluetooth button and pair in seconds.
Plug in any USB-MIDI keyboard via a USB-C hub. MIDI devices are detected instantly, no setup required.
The audio engine runs two parallel signal paths: a natural hall reverb and a dedicated shimmer bus that pitch-shifts every note +1 octave before feeding it into a cathedral reverb — the classic shimmer halo. Both are continuously adjustable with the FX sliders.
Pads, Keys, Strings, Brass and Synth — including a Korg D1 E-Piano. Every preset has pre-dialled reverb, shimmer and delay settings.
Sound keeps playing when the screen locks or you switch to sheet music apps. Perfect for live use.
Adaptive layout automatically adjusts for iPhone and iPad in any orientation.
Full sustain pedal support via MIDI CC 64. Works with any standard expression pedal.
The Akkorde tab names every chord you play in real time — maj7, m9, sus4, inversions with slash notation and more. 25+ chord qualities supported.
Every chord is logged to a scrollable history trail as you play. See your progression at a glance — great for transcribing or analysing improvised passages.
The built-in piano keyboard shows held notes in purple and sustained notes in amber, so you always know exactly what's sounding.
Tap the ▶ button to hear a live arpeggio demo — no keyboard required. Great for trying out presets on the go.
Every note you play is split into two parallel signal paths. Both mix at the output — controlled by the Reverb and Shimmer sliders in the FX Mix panel.
The shimmer path shifts the audio up a full octave before feeding it into a very long cathedral reverb (100% wet). What comes out is a bright, ethereal halo one octave above every note — the defining shimmer sound heard on ambient pads since the 80s. Turn the Shimmer slider up for an otherworldly, spacious feel; pull it back for a drier, more intimate tone.
From ethereal pads to cutting synth leads — all dialled in and ready to play.
Use Bluetooth LE for a wireless setup, or a USB-C hub with Power Delivery for a wired rig that keeps your device charged.
Wireless: Attach a BLE MIDI adapter (e.g. Yamaha MD-BT01) to your keyboard and tap the Bluetooth button in MIDI Shimmer to pair. Wired: Plug a USB-C hub into your iPhone or iPad and connect your USB-MIDI keyboard.
Your MIDI keyboard will appear automatically in the MIDI monitor at the top of the screen. The status pill turns green when the audio engine is running.
Tap any preset card to load it. Adjust Reverb and Shimmer mix with the sliders. The sound routes out of your USB audio interface automatically.
The app requires a SoundFont file bundled inside it. Make sure the app is fully installed and the audio engine status pill shows ACTIVE (green). If it shows OFFLINE, tap it once to restart the engine. Also check that your device volume is not muted.
USB: Connect the keyboard before opening the app, or tap the ↺ refresh button in the top-right corner to re-scan MIDI devices. Make sure you are using a USB-C hub.
Bluetooth LE: Tap the Bluetooth button (〇) in the Synth tab header and select your device from the list. Make sure the BLE MIDI adapter is powered on and within range.
Background audio is enabled by default. If sound stops, go to Settings → MIDI Shimmer and make sure the app has not been restricted by Low Power Mode or Focus mode settings on your device.
Crackling usually means the USB hub is not providing enough power. Use a hub with Power Delivery (PD) rated at 30 W or higher. Avoid daisy-chaining multiple passive hubs.
MIDI Shimmer listens for MIDI CC 64 (standard sustain pedal). Make sure your pedal is connected to the MIDI keyboard's pedal input, not a separate USB port, and that the keyboard is set to transmit CC 64.
MIDI Shimmer requires iOS 16.0 or later. It runs on iPhone and iPad. An Apple Silicon Mac is not supported at this time.
If your issue isn't covered above, please send an email and I'll get back to you as soon as possible.
✉︎ support@midi-shimmer.app