Piano roll, tempo and arrangement
Three views over the same song: the roll for note-by-note work, a tempo lane for timing changes, and an arrangement view for seeing the whole piece laid out track by track.
No upload, no install
Edit the MIDI you just converted
Fix timing, reshape velocity, move stray notes, then export a clean .mid for your DAW. Built as the next step after conversion — not a generic “online MIDI editor” clone. Nothing you open here is uploaded.
What this is
Clean up after conversion, then export
MIDI files describe performance rather than sound: which notes, when they start, how long they last, how hard they were played. Editing one means editing those numbers, and a piano roll is the clearest way to see them — pitch up the vertical axis, time along the horizontal, note length as the width of each block.
Arrive from the MP3 to MIDI converter with a transcription already loaded, fix timing and velocity here, then export. The editor is signal, an open-source project used here under the MIT licence — we strip its third-party requests so the page keeps the same promise as the converter: what you open never leaves your machine.
Every track in one document
Add, duplicate, rename, recolour and reorder tracks, with solo, mute and ghost for each. Muted tracks stay in the file — muting is something you listen with, not something you lose.
Draw, shape and sweep notes
Pencil tool to place notes, plus line and curve tools that generate a run of notes or an ease-in/ease-out velocity sweep in one gesture instead of fifty clicks.
Velocity and controller lanes
A dedicated lane under the roll for how hard each note plays, plus lanes for pitch bend and hold pedal — the performance data a transcription tends to flatten out.
Snap, loop and nudge
Snap-to-grid for note placement and dragging, a loop range you can set from the ruler, and arrow-key nudging when you want a note a hair before the beat.
Export MIDI or audio
Write a standard .mid back out, or render the result straight to WAV or MP3 using the instrument you loaded. Useful for checking a part without opening a DAW.
Bring your own instrument
Ships with a piano bank, and you can load any SoundFont (.sf2) file of your own, or a synthesised track, so playback sounds like the instrument you are writing for.
Play it in from a keyboard
Connect a MIDI controller over Web MIDI and record into the roll, or use the on-screen keyboard and your computer keys. Octave up and down are one keystroke away.
Event list for the last five percent
When a note looks right but sounds wrong, the event list shows the raw MIDI data — the actual ticks, channels and controller values behind what you see on the grid.
Reads and writes standard .mid
Files arrive from any DAW, keep their track names, and leave as standard MIDI. Time signatures, tempo changes and program numbers come along with the notes.
In your language
The interface is translated — including 简体中文 and 繁體中文 — so you are not decoding English menu labels while trying to hear whether a chord is right.
Your song survives a reload
Reload the page and the editor brings the same song back — the file you arrived with is kept for the tab. Edits you have not exported are not kept, so save a version from the File menu once it sounds right. None of it is sent anywhere.
How to use it
Four steps from file to finished MIDI
- 01
Open a file
Drop a .mid anywhere in the editor, or arrive from the converter with your transcription already loaded.
- 02
Fix the notes
Pick the pencil or selection tool, draw and drag on the grid, and snap to the grid value you want. Arrow keys nudge, one or many notes at a time.
- 03
Shape the performance
Work the velocity lane so accents land where they should, add pitch bend or pedal where the original had it, and set a loop to hear the same four bars again.
- 04
Export
Save a .mid for your DAW, or render WAV or MP3 to hear it as audio. Nothing was uploaded at any point.
Comes with the converter
Audio in, edit it, export
Convert an MP3, WAV or OGG into notes, then hit Open in editor in the result panel. The transcription arrives here as a real .mid file, ready to clean up before it ever reaches your DAW.
Go to the converterFAQ
MIDI editor FAQ
Where does my file go when I open it?
Nowhere. There is no upload step in this editor — the file is read with the browser's own File API and parsed in the tab. Its fonts, its instrument samples and its code are all served from this site rather than pulled from a CDN, so nothing about your session leaves your machine.
Who wrote this editor?
The piano roll is signal, an open-source MIDI editor by ryohey, used here under the MIT licence. We vendor it, build it into this site, and patch a handful of things — its analytics tag and CDN dependencies are removed so it makes no third-party requests, and a small addition lets the converter hand your notes straight to it. The converter is ours.
Does it work offline?
Not from a cold start — there is no service worker, so loading the page with no connection will not work. What does happen is that a repeat visit re-uses what the browser already holds: the model weights, the piano bank and the fonts are all served from this site rather than a CDN, so coming back re-checks them instead of pulling nine megabytes of instrument down again.
Is there a one-click quantise?
Yes. Select the notes you want tightened and press Q. The same command sits in the Edit menu and in the piano roll's right-click menu, and it stays disabled until something is selected — so it can never quietly move a part you were not looking at. Ctrl/Cmd+Z undoes it, which makes trying a hard quantise and backing out cheap.
Can I export audio, not just MIDI?
Yes. Export Audio renders the song through the loaded instrument to WAV or MP3 inside the tab. It is a way to hear the arrangement without a DAW; for a finished production you still want the .mid and your own instruments.
Can I edit several tracks at once?
Two views, two levels. The piano roll edits one track's notes at a time, and which track that is you choose from the track list in the arrangement view. The arrangement view is where the whole song sits side by side, and a box-select there reaches across tracks — so one transpose or quantise can land on several parts. Both act on the selection, and both undo with Ctrl/Cmd+Z.
What if I have no MIDI file to start from?
Open the editor without a song and you get an empty project: add a track, draw notes, set the tempo and time signature, and export. Or run an MP3 through the converter first and start from a real performance.
Do I need a MIDI keyboard?
No. Everything can be drawn and edited with a mouse and the keyboard shortcuts. A controller over Web MIDI is a convenience if you want to play parts in rather than place them.