Personal project · Multi-app platform
seikatsu — Personal Super App
Solo — architecture, backend, and UI, end to end · 2026 – ongoing
Off-the-shelf apps are too rigid for how I actually track my life, so seikatsu is a self-built alternative: one authenticated shell with independent mini-apps underneath — a finance tracker, a kanban board, a books log, with a habit tracker and a wishlist manager next in line. Public sign-in is open at seikatsu.danylomorhun.com.
The Challenge
Each mini-app is a real, full-featured product in its own right — the finance tracker alone does double-entry bookkeeping with multi-currency support. Building several of those, with more planned, without the codebase collapsing into an unmaintainable pile meant the shared infrastructure (auth, workspace, design system) had to be genuinely reusable, not just copy-pasted between apps.
The Approach
- A shared internal library layer split from the apps themselves, so every mini-app draws from one data layer and one component library instead of duplicating either
- Each mini-app lives as its own self-contained slice — actions, components, and logic kept together — so the finance tracker, the kanban board, and the books log evolve independently without stepping on each other
- The finance tracker is a real double-entry ledger: every transaction posts balanced entries across accounts, not a flat amount-plus-category row, with multi-currency entries reconciled against cached historical exchange rates
- The kanban board's drag-reorder uses a positioning scheme that never requires rewriting sibling rows, so reordering one card stays a single write
- One workspace model and one sign-in system shared across every app — adding a new mini-app is a route and a slice, not a new auth system
The Outcome
3
apps shipped — finance, kanban, and books — with habits and a wishlist next
1 shell
shared auth, workspace, and design system across every app