Est. 2026 · Helsinki

Limecore

A personal OS suite, built in high school.

Three apps that sync to each other over Realtime. Local-first. Open source. Helsinki.

Try Nexus in your browser ↗ GitHub ↗
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Projects

001
Nexus Command Center

A local-first life dashboard. Finance, studies, fitness, and tasks — synchronised across your devices, powered by your own API keys.

The hub of the suite. Reads workouts from LimeLog and study hours from StudyDesk over Supabase Realtime, plus its own finance, tasks, goals, and reading modules. Dexie + IndexedDB local-first, BYO API keys, biometric unlock, and a cross-module weekly review no single-purpose tracker can produce. On F-Droid for Android, with a full desktop edition in the browser.

React TypeScript Capacitor Dexie Supabase Tailwind Zustand
Local-first
GitHub ↗ F-Droid ↗ Open in browser ↗
Nexus home screen showing today's habits, a work check-in, a life-patterns insight, and budget, GPA, workout and task summaries
Home
Nexus goals screen listing tracked goals with progress bars across modules
Goals
Portfolio screen with holdings, allocation donut, and multi-currency totals
Portfolio
Weekly review screen synthesising workouts, study hours, and finance into one recap
Weekly Review
What-if simulator projecting net worth from adjustable contribution and growth assumptions
What-If
Fullscreen workout mode with the current set, target reps, and a persistent rest timer bar
Lock in
Training phase view showing the periodised block schedule and current mesocycle
Phases
002
LimeLog

Periodized workout tracker built for competitive athletes. Log sets, track vertical jump, work around injury restrictions, and get phase-aware progression insights. Writes into Nexus Fitness over Realtime. Android only — F-Droid submission in review.

React TypeScript Vite Zustand Capacitor
Local-first
GitHub ↗
Course list with per-subject grades on the IB 1 to 7 scale and a running average
Grades
Pomodoro timer set to a 25 minute focus block, with duration presets, a Lock In control, and a course picker for logging the session
Pomodoro
003
StudyDesk

Study planner for IB (1–7) and US (4.0) grading. Course list, Pomodoro logger, assignment and exam calendar. Writes into Nexus Studies over Realtime — what you log here surfaces in the hub. On F-Droid, plus a desktop edition with month and week grids in the browser.

React Capacitor Supabase Android
Local-first
GitHub ↗ F-Droid ↗ Open in browser ↗
// Side experiments
x01
Krata

Project-scoped AI command center. Bloomberg terminal for thinking. Structured, fast, no bloat.

Paused
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The Suite

Three apps, one data graph.

// one data graph
Limecore data graph LimeLog and StudyDesk write workout and study data into one shared Supabase project; Nexus Command Center reads from it in about 1.5 seconds. WRITER LimeLog workout sets WRITER StudyDesk grades · sessions REALTIME Supabase one project · RLS HUB · READER Nexus life score · review ~1.5s // last-write-wins · offline outbox · local-first Limecore data graph LimeLog and StudyDesk write workout and study data into one shared Supabase project; Nexus Command Center reads from it in about 1.5 seconds. WRITER LimeLog workout sets WRITER StudyDesk grades · sessions REALTIME Supabase one project · RLS HUB · READER Nexus life score · review ~1.5s // last-write-wins · offline outbox · local-first

LimeLog logs your set. StudyDesk logs your Pomodoro. Both write into the same Supabase project. Nexus Command Center reads — workouts surface in Fitness, study hours surface in Studies, weekly reviews pull from both. Cross-app updates land in ~1.5 seconds via Realtime, last-write-wins, offline outbox queued.

Local-first via Dexie / IndexedDB. Cloud sync over Supabase. End-to-end identity with email/password or Google OAuth. Biometric unlock and PBKDF2-SHA256 PIN with tiered brute-force lockouts on the hub.

No third-party data brokers. No subscription. Bring your own API keys for market data. The whole stack costs zero per user beyond what you choose to pay your providers.

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How I build

AI-in-the-loop
Local-first
TypeScript
Real device, not just emulator

Limecore ships fast because most of it is built with AI in the loop. Claude and Cursor write a serious share of the code; my job is architecture, taste, and the boring 20% that decides whether a thing is actually shippable.

Local-first by default, because cloud-first SaaS is what these apps are reactions against. TypeScript everywhere. Tested on a real Android device, not just emulators. Every release on every app goes through the same security checklist: CSP, secret-detection pre-commit, AndroidManifest hardening, source maps off in production.

Build logs and architecture writeups coming soon.

Blog ↗build logs & writeups
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About

HEL
Helsinki, Finland
4
Projects in flight

Limecore is a one-person studio based in Helsinki, run by a high-school student learning to ship real software in production. Tools that don't exist yet — life dashboards, training systems, study apps, AI infrastructure.

Local-first by default. Secure at rest. Designed for one person at a time, architected for more. Built because the existing options are too slow, too bloated, or too generic — and to learn what real shipping actually takes. Everything ships under Limecore.

Android Local-first Open source Life dashboards AI/LLM Fitness