Low-level truth
Notes shown in the piano roll are a projection of the original event timeline. Program, controller, pressure, pitch-bend, SysEx, and metadata events remain part of the document.
Private by default
Edit MIDI in your browser
Open a Standard MIDI File, choose the exact job you need, and export the result without uploading the file. Editing and preview playback run locally in your browser.
Focused MIDI tools, one shared engine
Every tool uses the same event-preserving MIDI core, with a workflow tailored to the change you need.
Keep the file intact around your edit
Honest preview
The player uses a lightweight browser synth for timing and note checks. It is not marketed as SoundFont playback or final-quality rendering.
Undo as one action
Transpose, tempo, quantize, and velocity changes enter history atomically, so one Undo restores the complete state before that operation.
What an online MIDI edit actually changes
A Standard MIDI File stores timed musical instructions rather than recorded sound. Notes are paired note-on and note-off events; tracks can also carry tempo changes, program selections, controller values, pitch bend, channel pressure, SysEx, and text metadata. EditMIDI keeps that event timeline available while the piano roll gives you a practical view of notes and timing.
Focused operations change only the event fields they describe. Transpose moves pitched notes, the tempo changer replaces the tempo map, quantize aligns note boundaries to a grid, and the velocity editor changes note-on intensity. Events outside the selected operation stay in the document, and an untouched export returns the original source bytes.
A reliable browser MIDI workflow
Open the file in the MIDI player first when you only need to inspect timing, track layout, mute or solo parts, scrub, or loop a range. Use the full MIDI editor when you need several changes in one pass. For one clear job, the transpose, tempo, quantize, and velocity pages provide a shorter path with the same underlying MIDI engine and the same Undo history.
Preview each change, compare it with the previous state, and download a new file instead of overwriting your source. Then audition that export in the synthesizer, sampler, or DAW that will receive it. MIDI sound depends on the destination instrument and program mapping, so browser playback is a timing check rather than a promise of final rendered audio.
File privacy, supported formats, and limits
Core parsing, editing, preview, recovery, and MIDI export run in your browser. Opening a local tool does not upload the file. After an edit, the browser keeps one recovery copy in IndexedDB on this device until you replace it or clear it. Creator Cloud is a separate, explicit action and is not required for any free local tool.
EditMIDI accepts Standard MIDI File Type 0 and Type 1 with PPQ timing. A file can be up to 5 MB and contain up to 20,000 events. These limits keep editing responsive and make failures clear before partial work begins. SMPTE time division and final-quality WAV or MP3 rendering are not presented as supported local features.