🎵 Key Detector & Transposer

Detect the musical key & BPM of any audio in your tab, then transpose songs in real-time on YouTube. Built for musicians.

Instantly identify the musical key and tempo of any audio playing in your browser — YouTube, Spotify, SoundCloud, or any other site. Key Detector uses professional-grade audio analysis to give musicians, DJs, worship leaders, and producers accurate, actionable results in seconds. ── HOW IT WORKS ── Key Detector captures your tab's audio and runs it through the Krumhansl-Schmuckler key-finding algorithm with a chromagram (pitch-class energy analysis). All processing happens 100% locally in your browser. No audio is ever recorded, uploaded, or transmitted. ── CORE FEATURES ── 🏆 Verdict Mode Accumulates audio over a configurable window for maximum accuracy. Choose 15s or 30s (free), or 45s / 60s (Pro). The result includes the detected key, mode (Major/Minor), a confidence score, tempo in BPM, and the top alternative keys so you can make an informed decision. ⚡ Real-Time Mode Watch the key and BPM update live as the song plays. The chromagram ring visualizes pitch-class energy in real time — great for modulating tracks or songs with multiple key sections. 🎛️ Studio Mode — Speed & Transpose (YouTube) Control playback speed (0.25× to 2×) without changing pitch. Pro users can also transpose the pitch of any YouTube video in real-time by up to ±12 semitones using SoundTouch audio processing — perfect for learning songs in a different key or adapting worship music to your vocal range. 📜 Session History Every result is saved automatically so you can compare keys across songs. Pro users get unlimited history; free users get the last 5 results. ── DISPLAY OPTIONS ── • ♯ Sharps or ♭ Flats notation • 8B Camelot Wheel notation for DJ harmonic mixing (Pro) • Toggle BPM visibility on or off • Set your default tab on open (Verdict / Real-time / Studio) ── PRO FEATURES ── Upgrade once, use on every Chrome you sign into. Pro unlocks: ✓ Real-time Transpose — change the key of any YouTube song ✓ 45s & 60s Verdict windows — maximum precision for complex songs ✓ Camelot Wheel notation — standard DJ harmonic mixing system ✓ Unlimited session history ✓ Side Panel mode — persistent wide panel that stays open while you browse ✓ Cross-device license — log in with your email to restore on any computer ── PRIVACY ── All audio analysis is performed locally using the Web Audio API. Key Detector never records, stores, or transmits your audio. The extension only requests the permissions it actually needs. ── PERFECT FOR ── - Musicians learning songs by ear - Worship leaders transposing songs to fit vocal ranges - DJs building harmonically compatible playlists - Producers identifying the key of samples and loops - Music students developing relative pitch and theory skills - Anyone who wants to know what key a song is in — instantly Stop guessing. Open Key Detector, press Start, and know the key in seconds.