Load two songs from your device and mix them like on DJ decks: scrolling waveforms with a beat grid, automatic BPM detection and one-click sync, pitch faders, cue and hot cues, beat loops, 3-band EQ with kills and an equal-power crossfader. Record your mix and save it as WAV or MP3 — nothing is uploaded.
Last updated:
A
B
00:00Two demo loops are loaded. Press Play on both decks, then hit Sync on deck B.
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How to use the Online DJ Mixer
Load a track into each deck with Load track (or use the demo loops that are already loaded).
Start deck A with Play and set the crossfader toward A.
Beatmatch deck B: press Play, then Sync to match its tempo and beats to deck A; fine-tune with the pitch fader or the « » nudge buttons.
Blend: cut the low EQ on the incoming deck, move the crossfader to the middle, then swap the bass and fade over to B.
Record: press Record mix before you start, Stop recording when done, then Download recording.
Pitch fader math: matching two tempos
To play a track at a new tempo you change its speed by (target BPM ÷ original BPM − 1) × 100%. The pitch moves with it: the shift in semitones is 12 × log2(target ÷ original).
From
To
Pitch fader
Pitch change
120 BPM
124 BPM
+3.33%
+0.57 semitones
124 BPM
128 BPM
+3.23%
+0.55 semitones
128 BPM
124 BPM
−3.13%
−0.55 semitones
126 BPM
140 BPM
+11.11%
+1.82 semitones
87 BPM (hip-hop)
174 BPM (drum & bass, half-time)
0% (exact double)
none
Changes above about ±6% (one semitone) start to sound noticeably higher or lower; that is why DJs usually mix tracks within a few BPM of each other.
A simple transition, step by step
Prepare: with deck B paused, find its first downbeat in the zoomed waveform and press Cue.
Cut the bass of deck B (Low EQ all the way down) so two kick drums and basslines don't clash.
Start on the phrase: press Play on deck B at the start of a new 8- or 16-bar phrase of deck A, then press Sync.
Bring it in: raise B's channel fader or move the crossfader to the middle over 8–16 bars.
Swap the bass: on a downbeat, cut A's low EQ and restore B's.
Finish: move the crossfader fully to B and stop deck A.
Mixer reference
Control
Range
Details
Gain
−12 to +12 dB
Level-match quiet and loud tracks before the fader
High EQ
−26 to +6 dB
High shelf at 3.5 kHz (hi-hats, vocals' air)
Mid EQ
−26 to +6 dB
Bell at 1 kHz, Q 0.9 (vocals, synths)
Low EQ
−26 to +6 dB
Low shelf at 220 Hz (kick and bass); −26 dB works as a kill
Crossfader
A ↔ B
Equal-power curve: both decks at −3 dB in the center, so the volume stays constant
Double-click any EQ, gain or pitch control to reset it.
Frequently asked questions
How does the BPM detection work?
The track is split into 11.6 ms frames, and sudden rises in bass and treble energy are turned into an onset curve. The tempo is the repetition period that best matches that curve (autocorrelation over 60–190 BPM), folded into the 80–170 BPM range, and the beat grid starts at the offset with the most onsets. If a song shows half or double the real tempo, press ×2 or ÷2.
What does the Sync button do?
It sets the pitch fader so the deck's tempo equals the other deck's current tempo (for example 124 BPM to 128 BPM is +3.23%), and if both decks are playing it jumps to the same position within the beat so the kicks line up. Changing the pitch fader afterwards turns sync off.
Does the pitch fader change the key of the song?
Yes. Like a turntable or a CDJ without key lock, speeding a track up by 3% also raises its pitch by about half a semitone (a 6% change is one semitone). Small adjustments are normal in DJ mixes.
How do cue points and hot cues work?
While a deck is paused, Cue stores the current position; while it plays, Cue jumps back to that point and pauses. Hot cues 1–4 store a position the first time you press them and jump there instantly afterwards. ✕ clears all hot cues on the deck.
How do I record my mix?
Press Record mix, perform your mix, then press Stop recording. The master output (after crossfader and master volume) is captured sample by sample and saved as WAV, or as 192 kbps MP3 if the encoder can load. Long recordings need memory: about 10 MB per minute while recording.
Can I use songs from Spotify or YouTube?
No. Streaming services encrypt their audio and do not allow it to be loaded into other apps. Use audio files you own, such as MP3, WAV, FLAC or M4A files on your computer or phone. The files stay on your device.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.