The Only Complete Online MIDI Editor
Compose.
Edit. Play.
MidiPro.org brings professional-grade MIDI editing to your browser —
unlimited tracks, microtonal scales, real-time effects, and MP3/WAV export.
No installation required.
"MidiPro.org is the only Online Midi Editor."
— ClassicalArchives.com, the largest classical music site in the world
Core Features
Everything a composer needs.
All in your browser.
🎛️
Complete Control
View and edit the exact Pitch, Velocity, and Duration of every MIDI event. No other online program lets you do that.
🎚️
Unlimited Tracks
Each track can be assigned a different Instrument and MIDI Channel, with Reverb, ADSR Envelopes, Low-pass Filters, and LFO Modulators.
▶️
MIDI Player
Start playback at any position. Solo or Mute individual tracks. The event list scrolls in sync so you always know what's playing.
🎹
Easy Note Entry
Add notes by clicking on a virtual synth keyboard. The Step By setting controls the default time distance between notes.
📋
Copy Range
Select a Start and End range, then copy those notes to the same track or any other track — instantly.
✂️
Edit Range
Delete, Transpose, Insert Blank Space, Change Durations, or Change Velocities for any selected time range.
🥁
Audio Import & Drum Loops
Import audio files and map them to MIDI notes. Includes 11 two-bar drum loops synced to any tempo.
📦
MP3 & WAV Export
Output audio from the MIDI player (or any audio source) to MP3 or WAV files — directly in your browser.
🔀
Split or Double Tempo
Match the tempo of any drum sample without altering pitch. Split or double all durations to shift between 120 and 240 BPM in one click.
🎼
Microtonal Music
Normal music uses 12 chromatic tones per octave. MidiPro.org supports 48 microtones per octave, each separated by a 1/8 step.
No custom scales required — click [Microtonal] on any track and add plus signs to raise a pitch in 1/8-step increments.
For example, G++ is 1/4 step higher than G.
The three microtones (+, ++, +++) are sent to three separate MIDI channels, raised by 1/8, 1/4, and 3/8 steps respectively.
→ Complete description of Microtonal features
Unique Feature
The Patterns feature will
change how you create music.
Imagine entering just two notes, and your entire bass track is generated.
Enter three more, and your rhythm guitar is done.
Patterns create new notes for your entire song (or a time range), with the same
relative position to the chords and keys you enter. This is fundamentally different
from transposing — the root, 3rd, and 5th always match the chord, while scale-degree notes
respect the current key.
Example: Giant Steps by John Coltrane — Pattern input: C E F G
| I | II | III | IV | V | VI | VII |
|---|
| Chords | BM7 D7 | GM7 Bb7 | EbM7 | Am7 D7 | GM7 Bb7 | EbM7 F#7 | BM7 |
| Keys | B G | Eb | | G | Eb | B | |
| Pattern | B D# D F# | G B Bb D | Eb G Ab Bb | A C D F# | G B Bb D | Eb G F# A# | B D# E F# |
Example: Pattern C E G A
| C | E | Am | F | F# | G |
|---|
| Chords | C | E | Am | F | F# | G |
| Keys | C | | G | C | | |
| Pattern | C E G A | E G# B C | A C E F# | F A C D | F# A# C# D | G B D E |