MIDI Merger

Combine local MIDI files as simultaneous tracks or join them end to end, then download one editable format-1 MIDI — without uploading anything.

Combine MIDI files

Layer complete MIDI files together or join them end to end, then download one editable format-1 MIDI.

No upload

Choose two to sixteen .mid or .midi files, up to 10 MB each and 30 MB total. The files stay in this browser.

Drop MIDI files here or browse

.mid/.midi · 2–16 files · 10 MB each · 30 MB total

Choose two or more MIDI files to begin.

Need separate parts instead? Use the MIDI Splitter. To inspect the merged result, open it in the MIDI Player.

How to merge MIDI files

  1. 1. Choose the files. Select or drop two to sixteen .mid or .midi files. The merger inspects their tracks, events, duration, and timing locally.
  2. 2. Set the order and mode. Move files into position, then choose Layer together for simultaneous parts or Join end to end for consecutive segments.
  3. 3. Check and download. Review the exact timing plan, resolve any compatibility warning, and create one format-1 MIDI with a conductor track plus the retained source tracks.

Layer together versus Join end to end

Layer together keeps every source track separate and starts every file at its original tick. This is useful for combining piano, bass, drums, or other parts that belong on one shared musical timeline.

Join end to end shifts each whole file after the previous file's final tick. It adds no gap, overlap, crossfade, trimming, or bar snapping, so phrases, movements, and sections follow the visible file order exactly.

Why file order and the timing master matter

In Layer mode, file 1 supplies tempo, time-signature, and key-signature changes. Later files keep their musical event positions but follow that master timeline, so moving another file into the first row can change elapsed playback time. In Join mode, order sets the segment sequence and every boundary restores standard defaults before applying that file's own clock events.

PPQ rescaling and SMPTE timing

PPQ describes musical ticks per beat. When PPQ values differ, the merger uses their exact least common multiple when it fits the MIDI header. Unusually large combinations fall back to the first file's PPQ and use integer rational rounding to the nearest tick; the workbench reports that before export.

SMPTE describes ticks against an absolute frame clock. SMPTE files can merge only when every active file uses the same supported frame rate and ticks per frame. PPQ and SMPTE files are not aligned by guesswork, and incompatible SMPTE divisions are not converted silently.

MIDI format 0, 1, and 2

Format 0
One source track contains the file's events. It becomes one retained source track beside the merged conductor.
Format 1
Synchronous source tracks stay separate and retain their original track order. Clock-only tracks are extracted into the merged conductor.
Format 2
Tracks are independent sequences without one file-wide timeline. The merger rejects format 2 and directs you to split those sequences first instead of flattening unrelated timing.

Preserved tracks, events, and format-1 output

Notes retain pitch, velocity, channel, order, and musical position. Programs, every controller number, pitch bend, note and channel aftertouch, text, lyrics, names, prefixes, markers, cues, copyright, sequence data, SysEx, sequencer-specific data, and represented unknown metadata remain in their retained source tracks when they are not global clock events.

The download is always format 1: one conductor track holds the chosen tempo, meter, and key timeline, followed by each retained source track in visible file order and original track order. The merger rebuilds one final end marker per track and does not collapse tracks by channel, invent track names, quantize notes, or choose instruments.

Merging MIDI is not mixing audio

MIDI stores performance instructions, not recorded sound. Combining MIDI files does not render instruments, balance audio levels, make a waveform, separate stems, or create a crossfade. To hear a local result, open it in the MIDI Player. To render a MIDI with General MIDI sounds, use the MIDI to WAV.

Private, local, and bounded

Every selected MIDI is read, inspected, combined, and downloaded in your browser. Nothing is uploaded or stored. Choose two to sixteen .mid or .midi files, up to 10 MB each and 30 MB total. Each file may contain up to 256 source tracks; an active merge may retain up to 512 tracks and include up to 500,000 raw events across the selected set.

MIDI Merger FAQ

Is the MIDI merger free, and do I need an account?
The MIDI merger is free to use and does not require an account. Choose two to sixteen local MIDI files, select how they should combine, and download one merged format-1 MIDI.
Are my MIDI files uploaded or stored?
No. The files are read, inspected, merged, and downloaded in your browser. They are not uploaded, transmitted, saved to an account, or stored after you leave or reload the page.
What is the difference between Layer together and Join end to end?
Layer together starts every file at its original tick so the parts play simultaneously. Join end to end places each whole file after the previous file with no automatic gap, overlap, trimming, or bar snapping.
What happens when the source files use different tempos?
In Layer mode, the first file is the timing master and later files align by musical ticks under its tempo, meter, and key timeline. In Join mode, every segment restores its own tempo, time-signature, and key-signature events at its boundary.
Can the merger combine MIDI files with different PPQ values?
Yes. It uses an exact shared PPQ division when the least common multiple fits the Standard MIDI limit. For unusually large high-PPQ combinations, it uses the first file's PPQ and rounds rational event positions to the nearest tick, with that decision shown before download.
Which MIDI formats and timing divisions are supported?
The merger accepts Standard MIDI format 0 and format 1 files with valid PPQ timing, or files that all use the same supported SMPTE frame rate and ticks per frame. Format 2 is rejected because its tracks are independent sequences; split those sequences first instead of flattening them silently.
Are tracks, channels, and MIDI events preserved?
Yes. Every retained source track stays separate in the output, with its channels, notes, velocities, programs, controllers, pitch bends, aftertouch, text, lyrics, SysEx, and other represented non-clock events. The merger extracts global clock events into one conductor track and does not collapse tracks by channel.
Does merging MIDI mix or render audio?
No. MIDI stores notes and performance instructions rather than recorded sound. The merger combines MIDI tracks and timelines; it does not mix audio, render instruments, make a WAV, separate stems, quantize performances, or infer musical alignment.

Continue working with the MIDI

  • MIDI Splitter — separate one file into exact track or channel parts before or after a merge.
  • MIDI Player — inspect and play the merged file with piano-roll, score, and tab views.
  • MIDI to WAV — render the merged MIDI as downloadable stereo audio.
  • Progression Generator — create a new chord progression and download it as MIDI.