I am looking for a piece of software (standalone or plugin - doesnt matter) that is a pure midi editor/piano roll, multitrack, AND lets me freely change tempo, key and time signature throughout the music.

Is this a thing that exists?

 

http://www.midieditor.org/
Yeah but I don't know, at the end I came back to Reaper.

Edit: No staff score if I remember.

 

Each of the following recommendations are light weight and well optimized software. They also all provide MIDI graphical editing, MIDI event list editing, CC automation lanes, clips as well as patterns, etc. Everything you need for proper MIDI editing.


Sekaiju (Windows only).
It's free! Still actively updated & in development. Very much in the vein of oldschool midi sequencers like Cakewalk 3.0 and earlier (it even loads old Cakewalk files!). This one is strictly MIDI and completely powerful. High recommended!


REAPER
Can't go wrong. Although it has a fully featured audio engine, you can easily customize the windows and toolbars to be almost entirely MIDI orientated.


Sagan Metro
Jeremy Sagan has added a lot of audio bells and whistles over the years but it its core it is a fully-featured, proper MIDI sequencer with heritage going back to the late 1980, and that's why I mention it. It rocks and I'm fond of it, but it ain't free ($30 for Metro SE).


There are others I can recommend but the price goes up and/or the accessibility goes down.
Digital Performer is an incredible MIDI sequencer, so is Opcode Vision.

Pure MIDI sequencers are a passion of mine and so is MIDI timing (and all its issues). For a long time I wanted the leanest, tightest MIDI only software sequencer. With very few exceptions, they just don't build 'em like that anymore. I've tried pretty much everything under the sun.

 

Last edited: Jun 10, 2026

Just a personal addendum to my last post:

After much careful study & testing over the course of a year, including across multiple computers & operating systems and hardware & software sequencers, what has worked best for me is:

REAPER on an extremely lean Mac Pro 5'1 running OS 10.11 that launches from an Automator script in renice mode (high CPU priority terminal command) and uses (2) Edirol UM-3ex for MIDI interface. Absurdly low jitter output in that configuration.

 

Wow this one is great!! Exactly what I am looking for and more!!

 

There's this online one: https://signalmidi.app/

 

Temper standalone/VST does this and it takes heavy inspiration from Bars & Pipes from the Amiga days. So it means it's designed to quickly manipulate MIDI both with editors but also with MIDI FX. So you have tempo/meter/scale/chord tracks for when you're working on prog tunes.

Yeah, the plugin version is 32-bit only as the development has ceased a while ago. The standalone can host VSTs for auditioning but again it's 32bit.

 

Yeah, Temper is a great option as well!