Purpose
BPMKeyFinder is an online analysis tool for DJs, music producers, and music educators, used to confirm the tempo (BPM) and musical key of an audio file before playback or mixing, and to provide the Camelot code suitable for harmonic mixing. The tool emphasizes local processing and privacy, making it suitable for quickly analyzing a local music library in the browser.
Main capabilities
- BPM detection: Automatically estimates tempo from the audio signal. The materials also note that detection results may appear as half or double the actual tempo, and it is recommended to verify by tapping along.
- Key and Camelot code: Displays both the musical key and the Camelot wheel code, for example C major is 8B and A minor is 8A; it also detects major/minor mode. Adjacent numbers or the corresponding relationship of the same number on the A/B ring can serve as a starting point for harmonic mixing.
- Key strength score: Describes how well the algorithm fits a certain key profile; the materials explicitly state that it is not the probability that the key is correct. Relative major/minor keys and altered harmony may cause ambiguity.
- Share result link: After analysis, a share link can be generated. The link contains the file name and analysis results in base64 encoding (not the audio). The link does not expire and requires no server storage; anyone who obtains the link can view these results.
- Example analysis: When no file is available, a 16-second C major example generated on the device can be analyzed.
How to use
- Select an audio file: Drag and drop or click to select a local MP3, WAV, FLAC, M4A, AAC, OGG, or AIFF file. The materials explain that browser decoding support varies, long tracks use more memory, and if necessary a shorter clip can be tried first.
- Local analysis: After the analysis engine loads, the browser decodes the file locally and uses Essentia.js to estimate tempo and key; the audio is not sent to a server.
- View and share: Read the BPM, major/minor, Camelot code, and key strength score; you can continue analyzing the next file or copy the result link.
Use cases
- Touring and club DJs: Confirm track tempo and compatible keys before going on stage, so transitions between newly promoted tracks or custom edits stay musically smooth.
- Music producers and editors: Align samples, stems, and cue points to the project grid, and quickly determine whether vocal or instrumental tracks need transposition or time stretching to fit the mix.
- Educators and choreographers: Provide students or dance troupes with reliable BPM and key information, without expensive or complex software, for classroom and choreography music planning.
Limitations and notes
- Free and scope: The current analyzer is free, requires no account, has no daily analysis quota, and no paid Pro plan; it processes only one local file at a time and does not provide batch queues, CSV export, or saved analysis history.
- Local files only: Currently only local audio files are accepted; tracks cannot be retrieved from YouTube, Spotify, or other streaming links.
- Privacy: All analysis is performed entirely in the browser; audio is not uploaded, stored, or queued to any server, and nothing is cached beyond the local session. Shared links contain only analysis metadata, not audio, but anyone with the link can view the results, so only share it with people you trust.
- Accuracy and formats: For live recordings, sparse percussion, short clips, or pitch-shifted songs, results may be ambiguous; BPM may appear at half or double speed; format support and available memory vary by browser, and if decoding fails, try WAV or a shorter clip.
