Download of NASequencer 1.0.4 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this free Mac application is Noriyoshi Abe. The program is included in Audio & Video Tools. According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software.
From the developer:
NASequencer is a text-based MIDI composer. It focuses on quick composing and easy management. Generally, plain-text is easy to edit and manage, however it can often be unreadable in music composition. NASequencer assists you in understanding the structure of a composition with real-time piano roll and event list previews. Additionally, it assists you to check sound of ensemble by SoundFont synthesizer.
You may want to check out more Mac applications, such as Mixtikl 5, Noatikl 2 - Generative Music Lab or LividLooper, which might be related to NASequencer.