Hello — I'm Junichi, and I made Kosshi.
A few years ago I was writing a technical book and noticed that sketching the structure first made the writing go much more smoothly. Around the same time I was juggling several personal projects, with information drifting apart across different tools, and I started to want an outliner of my own.
What I was after was something that worked the same way on Mac and iPhone, could place images alongside text, and kept its data on my own devices. I couldn't find it, so I made one. That's Kosshi.
It's a native Mac and iOS app, with a rendering engine written from scratch, designed to stay smooth even with large outlines. Sync is over iCloud — no account, no server I run; your data lives only on your devices and in your iCloud.
If you live in an outliner, I'd love to hear what you find.
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feels like a very honest builder story, you needed a calm, private outliner that worked the same way across Mac and iPhone, so you made one.I like the no-account/no-server approach. Outlines often hold unfinished thinking, not just polished notes.what was harder to get right: performance with large image-heavy outlines, or keeping the experience simple across both Mac and iOS?
Of the two, cross-platform was the harder one. The hard part wasn't really keeping the UX simple. It was one layer deeper. The rendering engine handles layout, text, Markdown, and images in one pipeline, and getting it to run cleanly through a single shared codebase across Mac and iOS is what took the most time. A change on Mac shows up on iPhone too.
Honestly, image-heavy outlines aren't something I've pushed hard on. Kosshi is built for outlines that are mostly thinking, with images as occasional anchors. One thing I did spend time on, though, is making sure rows off-screen pay no rendering cost, and that applies to images too. So having a lot of them spread across a large outline shouldn't really be a problem.
Kosshi
feels like a very honest builder story, you needed a calm, private outliner that worked the same way across Mac and iPhone, so you made one.I like the no-account/no-server approach. Outlines often hold unfinished thinking, not just polished notes.what was harder to get right: performance with large image-heavy outlines, or keeping the experience simple across both Mac and iOS?
Kosshi
@harshalvc_ai
Thanks, that's a kind read.
Of the two, cross-platform was the harder one. The hard part wasn't really keeping the UX simple. It was one layer deeper. The rendering engine handles layout, text, Markdown, and images in one pipeline, and getting it to run cleanly through a single shared codebase across Mac and iOS is what took the most time. A change on Mac shows up on iPhone too.
Honestly, image-heavy outlines aren't something I've pushed hard on. Kosshi is built for outlines that are mostly thinking, with images as occasional anchors. One thing I did spend time on, though, is making sure rows off-screen pay no rendering cost, and that applies to images too. So having a lot of them spread across a large outline shouldn't really be a problem.
mailX by mailwarm
Kosshi
@othman_katim
Thanks, really appreciate it!