Very nice! Looks like OmmWriter. Is it open source?
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After 6 years and 2 million words of daily writing I feel like I've learned enough to make Ensō simpler and more accessible.
Related thread: https://news.ycombinator.com/item?id=38025073
Writing in program such as that is a very personal experience, and doing it on a non open source platform just seems off for me.