Updated October 2026 by Kamal Nasir
Apps that read a song's key, tempo or loudness usually do one of the three. Some listen through the microphone, some open audio files, and a few do both. Here is what each app does, going by its own App Store listing.
Finds the key of a song from live music through the microphone, from an audio file on the device, or from a set of chords you type in, with the analysis done on the device. Results can be saved, and a song that changes key can be analyzed part by part. App Store
From Antares Audio Technologies, the maker of Auto-Tune. It captures a few seconds of audio from a speaker, an instrument or a voice, returns the most likely key, and can send that key to an Auto-Tune session in a computer DAW. App Store
Finds the tempo of music through the microphone with no tapping, and keeps recalculating the BPM in real time. It can send the detected BPM to other MIDI devices. App Store
A loudness meter for LUFS and true peak, with spectrum and vectorscope views, that runs as an app or as an AUv3 plugin in hosts such as GarageBand. It can record from the microphone or an audio interface and analyze audio sent over Wi-Fi from a desktop DAW. App Store
Reads the key, mode, harmonic code, BPM, integrated loudness and true peak from files you own or from the microphone, on the iPhone with no account and no networking code. Sets inside a tempo window, a crate sorted by key or tempo, and streaming loudness targets are part of it. Needs iOS 27. About it ยท App Store
Yes. Several key finder apps listen through the microphone for a few seconds and return the most likely key and mode. Results are steadier from a clean audio file than from a noisy room.
Not as files. Apple Music streaming tracks are protected, so key and BPM apps work on audio files you own, on files shared into them, or on what the microphone hears.
Our entry in this category: BPM, Key and Loudness: Quint.
Published by Kamal Nasir, the developer of the apps marked Ours. Apps change, so check each one's App Store page for its latest features.