BPM, Key and Loudness: Quint

iPhone app by Kamal Nasir

Quint is a song key and BPM finder for iPhone that also measures loudness in LUFS, analyzing tracks on the phone with no account and no upload.

What it does

• Find the key, its mode and the BPM of a song file you own, or of one shared in from another app
• Hold the phone to a speaker for twenty seconds to read the key from the room
• Harmonic codes from 1A to 12B for mixing in key, with the Traktor style d and m notation as an option
• Integrated loudness and true peak, measured to ITU-R BS.1770 and compared against the published targets of streaming platforms
• Build a set that flows from track to track inside a tempo window you choose
• A crate of every reading, sorted by key, code, tempo or loudness, and a card to post with the key, code and tempo
• Analysis runs on the iPhone through Music Understanding, the framework Apple shipped in iOS 27, with no account, no sign in and no networking code

Questions people ask

How do I find the key and BPM of a song?

Run the song through a key and BPM finder app, either as an audio file or through the microphone. In Quint you import or share in a file you own, or hold the phone to a speaker for twenty seconds, and it shows the key, the mode, the harmonic code and the BPM.

What is the Camelot wheel in DJ mixing?

It numbers the 24 major and minor keys from 1A to 12B so that keys that mix well sit next to each other. Staying on the same code, moving one number up or down, or switching between A and B at the same number keeps a mix in key. Quint shows every track's harmonic code in this 1A to 12B convention.

What is LUFS and why does it matter for streaming?

LUFS measures perceived loudness across a whole track, as defined in ITU-R BS.1770. Streaming services turn tracks up or down to their own loudness target, so checking integrated loudness and true peak before upload shows how a master will be adjusted. Quint measures both on the phone.

Comparing apps? See the guide: Best song key and BPM finder apps for iPhone in 2026.

More apps by Kamal Nasir

• Kamera Pro: LiDAR Night Vision
• Nocturne: Card Value Scanner
• HydroNest Family Water Tracker
• Halo: Migraine Tracker
• IBS Tracker Food Diary: Fennel
• Litmus Label Reader
• Halal Scanner - Dalil
• ChartKey: Medical Keyboard
• Therapy Notes Keyboard NoteKey
• Drone Weather Hourly: Pitot
• Jolt: Tic Tac Toe

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.