Developed in 2004, BRELS MIDI Editor is a free, open-source (licensed under the GNU GPL) MIDI editor able to create and edit MIDI files with a simple, straightforward interface. The saved files have the smallest size possible. Their entire content is editable onscreen and the exact composition length is shown and controllable by the program. Yet, preexistent files can be cleaned and filtered, removing garbage and embedded malformations made by other tools.

The program presents a minimalist interface, from its installation, which just requires the extraction of the 7zip/ZIP/RAR file without any modification to the system, to its commands, all shown onscreen, without menus or indirect paths.

The source can be compiled with GCC with Strict ISO C options (-Wall, -pedantic and many others), preferrably in an IDE like Eclipse, to which it can be imported. You can use its internal API to incorporate MIDI funcionality in a Windows C application. You can read documentation of that API here (the text is quite ancient, has typos and is outdated regarding licensing). Check what's new in v0.08 in version history below the screenshot.