Key Detector – Musical Key & BPM Finder

Find musical key and BPM, practice with an interactive piano, and transpose YouTube with Pro. Analyze audio on your device.

🎵 KEY DETECTOR & TRANSPOSER Musical key finder, BPM detector and practice tools for Chrome. What key is this song in? Find a starting point for playing along, learning a melody or preparing a vocal performance. Key Detector estimates the musical key and tempo of audio playing in your browser tab, or analyzes an audio file on your device. No microphone required. Use the interactive piano and manual tap tempo to explore the result. With Pro, transpose YouTube videos and adjust playback speed to suit your practice. ✨ WHAT'S NEW IN 1.6.8.1c • Refreshed interface with clearer contrast and key and tempo together in one result card. • Green accents for high tonal affinity, amber for medium and coral for low affinity. • A redesigned Practice tools panel that keeps the reference piano and tap tempo together. • A red Stop button with white text, plus clearer keyboard focus and dialogs. • Fixes for interrupted analyses, file cancellation and the displayed destination key in Studio. 🔍 FIND THE KEY AND TEMPO • Detect major and minor keys from a 15- or 30-second sample; Pro adds 45- and 60-second options. • See the estimated key, BPM and three alternative key candidates. • Use Live mode for continuously updated key estimates while audio plays. • Review recent results in your local history and copy a result when needed. The tonal affinity score describes how closely the analyzed audio matches a tonal profile. It is not a probability that the answer is correct. Relative keys, changing harmonies and half- or double-time rhythms can produce ambiguous results. Try another musical passage and use your ear to compare. 📁 ANALYZE AUDIO FILES LOCALLY Open or drag in a recording, track or sample for key and BPM analysis without playing it in a tab. Supported formats include MP3, WAV, FLAC, OGG and M4A, subject to Chrome's ability to decode the file. Free includes one successful file analysis every seven days. Pro removes this quota. Both plans have a 250 MB file size limit. 🎹 PRACTICE TOOLS — INCLUDED FREE • Interactive reference piano from C4 to C5: click a key to hear its note. • Root-note selection and Chromatic, Major and Minor scale options. • Root and scale-note highlights that sync with your detected key. • Manual tap tempo: tap along to estimate the beat, then reset whenever you need. • A collapsible panel that remembers whether you left it open. 🎛️ STUDIO — YOUTUBE TRANSPOSITION AND SPEED CONTROL (PRO) Shift YouTube audio from −12 to +12 semitones without changing playback speed. Adjust speed separately from 0.25× to 2× while preserving pitch, or reset both controls to the original settings. Bring a song into a more comfortable vocal range, slow down a difficult passage or practice an instrumental part in a different key. When a suitable detection is available for the current video, Studio also shows the source and destination keys. ⭐ FREE AND PRO Free includes: • Detect and Live key detection. • BPM detection and manual tap tempo. • The interactive reference piano. • One successful audio-file analysis every seven days. • Access to your five most recent history entries. Pro adds: • YouTube pitch transposition and speed control. • Audio-file analysis without the weekly quota. • Longer 45- and 60-second detection samples. • Camelot notation for DJs and harmonic mixing. • Dark mode, the side panel and access to the full locally stored history. 🔒 PRIVACY AND COMPATIBILITY Audio analysis runs on your device. Your audio is not uploaded for analysis. Detection history and preferences are stored locally in Chrome. Pro purchases, account restoration and license checks use ExtensionPay and require an internet connection. Tab detection works on supported pages where Chrome permits audio capture. Restricted pages and protected media may not work. Studio pitch and speed controls are designed for YouTube. File support depends on the format and codec. Keep the popup open during tab analysis, or use the Pro side panel. Available in English, Spanish and Brazilian Portuguese. Requires Chrome 116 or later. Made for instrumentalists, singers, music students, teachers, producers and DJs who want a practical starting point for listening, learning and playing along. If Key Detector helps your practice, a review helps other musicians discover it.