BPM detection, key finder, chord detection, delay calculator, and scale reference. All free, all in your browser. Works alongside Reaper with no plugins or installs.
Reaper Does Not Include:
BeatKey fills all these gaps, free, in any browser tab.
Upload any audio file. Get exact BPM, musical key, and Camelot code in seconds.
Reaper use:
Set Reaper project BPM from the detected value. Confirm before warping loops with Reaper's audio item properties.
Click any Camelot key to see all harmonically compatible keys highlighted.
Reaper use:
Plan harmonic transitions before arranging clips on Reaper's timeline. Deep-link from BeatKey results pre-selects your key.
Detect chords in any audio file. Outputs chord name, timeline, and musical key.
Reaper use:
Find chords in samples before loading into Reaper. Build MIDI chord clips in the MIDI editor using the detected progression.
Get BPM-synced delay times for every note value. Tap tempo included.
Reaper use:
Switch ReaDelay to ms mode. Enter the dotted eighth value from BeatKey for rhythmic delay. Use quarter note for classic slapback.
Look up notes for any scale in any key. 18 scales including all modes.
Reaper use:
Use scale notes in Reaper's MIDI editor snap-to-scale feature. Program MIDI with only the diatonic notes visible.
Convert any note to Hz and vice versa. 808 tuning guide included.
Reaper use:
Get exact Hz for 808 root note. Tune samples using Reaper's pitch shift by semitones in audio item properties.
Drop sample into BeatKey
Go to beatkey.app, upload your sample. Get BPM, key (e.g. A minor), and Camelot code (8A) in seconds.
Check chord progression
Open chords.beatkey.app, upload the same sample. Get the full chord timeline. Common in soul samples: Dm7 - G7 - Cmaj7.
Set Reaper project tempo
File > Project Settings > BPM. Enter the detected BPM. Or right-click audio item > Properties > Timebase to match.
Pitch to your key (if needed)
Use beatkey.app/key-transposer to calculate semitone distance. Then in Reaper: select item, Shift+P > Pitch Adjust. Enter semitone count.
Tune your 808
Get the 808 root note Hz from notes.beatkey.app (C1 = 32.7 Hz, D1 = 36.7 Hz). Adjust pitch in Reaper audio item properties until it matches your key.
Set ReaDelay to BPM-synced ms
Go to delay.beatkey.app. Enter your BPM. Copy the dotted eighth value (e.g. 421ms at 128 BPM). Open ReaDelay, switch to ms mode, paste.
Set Project BPM from BeatKey
Open any audio file in BeatKey to get the exact BPM. Then in Reaper: File > Project Settings > BPM. Or right-click a media item > Item Properties > Timebase and set the detected tempo directly.
MIDI Snap-to-Scale with Scale Finder
In Reaper's MIDI editor, use the View > Scale Highlighting menu. Look up the exact scale notes from scales.beatkey.app first, then configure the scale in the MIDI editor to only show diatonic notes. Works for all 18+ scale types including Dorian, Phrygian, and Lydian.
Tune 808s with Note Frequency
Load your 808 sample into Reaper as a media item. Use notes.beatkey.app to find the Hz value of your target root note. Double-click the item in Reaper > Properties > Pitch Adjust (semitones) to match the target note. 808s on C1 = 32.7 Hz.
ReaDelay BPM-Sync in ms Mode
ReaDelay (Reaper's built-in delay plugin) has both note-division and ms modes. Switch to ms mode when you need exact values. Enter dotted eighth ms from delay.beatkey.app for The Edge-style rhythmic delay. Quarter note for simple slapback echo.
Verify Loop BPM Before Importing
Loop libraries often label BPM in the filename but are sometimes wrong. Drop the audio into BeatKey first to verify the real BPM before setting Reaper's project tempo to match. Prevents off-beat loops ruining your session.
Sample Flip Key Detection Workflow
Drop a sample into BeatKey to detect BPM and key. Use Chord Finder to detect the chord progression. Then in Reaper: import the sample, use Reaper's pitch shift to change key if needed (semitone count from key-transposer at beatkey.app/key-transposer), then slice and rearrange in the timeline.
| Feature | Reaper | BeatKey |
|---|---|---|
| BPM Detection from Audio | Tempo detection on import (sometimes inaccurate) | Exact BPM via Essentia.js WASM analysis |
| Musical Key Detection | Not built-in | Full key + Camelot code from audio |
| Chord Detection | Not built-in | Full chord timeline from any audio file |
| BPM Delay Calculator | No dedicated ms calculator (ReaDelay has note divisions) | Full table: all note values + tap tempo + reverb pre-delay |
| Scale Reference | MIDI editor scale highlighting (requires manual setup) | 18+ scales with all notes per key, instant lookup |
| Note Frequencies (Hz) | Not built-in | Full MIDI 0-127 table + Hz-to-note converter |
| Camelot Codes | Not built-in | Interactive Camelot Wheel with key detection |
| Price | $60 one-time + plugins | Completely free, no account |
| Browser Access | Desktop app required | Any browser, any device |
| Works on Unreleased Tracks | Yes (local DAW) | Yes (local browser WASM, no upload) |
| Mobile Access | Desktop only | Any mobile browser |
Does Reaper detect the key of a song?
No. Reaper does not include key detection from audio files. It can detect tempo (BPM) with some accuracy, but musical key detection is not a built-in feature. BeatKey detects both BPM and key from any audio file and shows the Camelot code for harmonic mixing.
How do I get BPM-synced delay in Reaper?
Reaper's built-in ReaDelay plugin has both note-division mode and millisecond mode. For exact BPM-synced ms values, use delay.beatkey.app, enter your project BPM, and copy the desired note value in ms. Dotted eighth note delay is 562.5ms at 100 BPM and 421.9ms at 128 BPM. Switch ReaDelay to ms mode and enter the value.
Can I use BeatKey tools on mobile with Reaper Mobile?
Yes. All BeatKey tools work in any mobile browser (iPhone, Android). If you use Reaper on iPad or Android tablet, you can open BeatKey tools in a browser tab alongside Reaper to detect BPM, key, and chords from audio files.
How do I tune an 808 in Reaper?
Use notes.beatkey.app to find the Hz value of your target note (C1 = 32.7 Hz for the lowest 808 root). Load your 808 as a media item in Reaper. Double-click > Properties > Pitch adjust (semitones). Count the semitones from your 808's root note to the target note. For example, if your 808 is tuned to C and you need D, pitch up +2 semitones.
Is Reaper free?
Reaper has a free 60-day trial, after which it uses a $60 discounted license (for personal/small business use). BeatKey tools are completely free with no trial period, no subscription, and no account required.
Free, no account, works in any browser tab alongside Reaper.