Individual Developer Studio

Small tools.
Real use.

I build things that remove the small frictions of everyday life.
No bloat. Just the one thing that needed fixing.

Products

Products

🌟
Premium ¥300/mo

Polaris

Turn vague ambitions into a clear roadmap through AI conversation, then make daily progress just by checking off actions.

  • AI generates mid-term goals and actions
  • Progress bars keep you motivated
  • Monthly review reports, auto-generated
  • Add to home screen (PWA)
Open App →

Tools

Tools

Small, fast, and solving exactly one thing.

📌
Notipop
A Chrome extension that saves selected text to Notion in one click.
Free Get started →
📅
FLOW YOTEI
No sign-up needed. Share a URL and let people pick a time — scheduling made simple.
Free Try it →
🖼️
SizeKit
Resize & convert images to recommended SNS sizes. Runs entirely in your browser — no uploads, no server.
Free Try it →

About

Who's building this

👨‍💻

Kobayan

Tokyo / IT manager by day / indie dev by night

I work as a manager at an IT company. Nights and weekends, I build things I actually want to use.
Not looking to go viral — just making tools that feel good in the hand.
The best moment is when someone uses something I made without thinking about it.

Next.js Firebase Chrome Extensions AI-assisted dev Vibe coding

Playground

Mini Game

Small games built between coding sessions.

Click first to focus · SPACE to jump · Hold for higher jump

Arrow keys or swipe · Merge tiles to reach 2048