On Releasing Setsuna, a Cross-Device Text Sharing Service

As the title says, I released Setsuna, a cross-device text sharing service, on 12/28.

デバイス間テキスト共有アプリSetsunaをリリースしました。https://t.co/FNbVd8ohHOhttps://t.co/8VPNjyX0K7

昔自分用につくって公開していたOSSを、Claude Codeに全面バックアップしてもらってリバイバルしたものです。…

— びーぐる (@beagle_dog_inu) December 28, 2025

(Since it was abbreviated, I’ll write it out here)
“This is a revival of an OSS I made for personal use a while back, with full backing from Claude Code. There are plenty of similar tools out there now and it’s nothing special, but I wanted to rebuild it once with modern tech as a learning exercise, so I released it.”

デバイス間テキスト共有サービスSetsunahttps://t.co/hjaJEAeu8ehttps://t.co/8VPNjyX0K7
バージョンは1.3.3になり、大体作りたい機能の開発が終わりました。

自力だと体感1ヶ月程度の実装が、Claude Codeのおかげで丸2日くらいで終わりました。確かに作業効率10倍くらいにはなってそうです。

— びーぐる (@beagle_dog_inu) December 29, 2025

Originally it was a personal project of the same name, built with (if I remember correctly) Node + Express + Socket.IO and Vue… something like that. But I couldn’t fix some minor bugs, and leaving something incomplete that I couldn’t maintain didn’t sit right with me, so I took it down.

Thanks to Claude Code, the result far exceeded the original in quality, design, and maintainability. And above all, the development speed. I started on the 27th, released v1.0.0 on the 28th, and completed all planned features (plus some extras) with the v1.3.3 release on the 29th. At this level, it really feels like there’s no place for humans anymore (especially in the coding phase).

I’d like to keep improving it whenever good feature ideas come up.