Loop

A self-hosted, privacy-first cycle tracking web app. Your data stays on your machine — no cloud sync, no accounts, no tracking.

Philosophy

• Lightweight — SvelteKit + SQLite, minimal dependencies, fast cold starts
• Private by default — all data stored locally in a single SQLite file you own
• Visually clean — focused UI, no clutter
• Self-hosted — run it on your laptop, home server, or Raspberry Pi

Features (planned)

• Daily cycle log: BBT, cervical mucus, bleeding, notes
• OPK strip scanning — camera-based LH surge detection via line ratio analysis
• Cycle calendar with pattern visualization
• Fertility window prediction
• Data export (CSV / JSON)

Stack

Layer	Choice
Frontend	SvelteKit + TypeScript
Database	SQLite via better-sqlite3
ORM	Drizzle ORM
Bundler	Vite

Getting Started

npm install
npm run db:generate   # generate SQL migrations from schema
npm run db:migrate    # apply migrations (creates data/loop.db)
export LOOP_PASSWORD='choose-a-long-password'
npm run dev           # start dev server at http://localhost:5173

If you want a dedicated session signing secret, also set LOOP_SESSION_SECRET. Otherwise Loop derives it from LOOP_PASSWORD.

Project Structure

src/
  lib/
    components/   # Svelte UI components
    server/       # Server-only: db connection, schema, queries
    stores/       # Svelte stores for client state
    utils/        # Shared utilities (date helpers, etc.)
  routes/         # SvelteKit file-based routes
    api/          # API endpoints (+server.ts files)
    log/          # Daily log view
    settings/     # App settings
drizzle/
  migrations/     # Auto-generated SQL migrations
data/             # SQLite database (gitignored)

Data & Privacy

The SQLite database lives at data/loop.db (configurable via DATABASE_PATH env var). It is gitignored by default. Back it up by copying the file.

Authentication

Loop uses simple single-user auth:

• Set LOOP_PASSWORD before starting the app
• Visit /login and enter that password
• A signed session cookie keeps you logged in for 30 days

OPK Example Images

Place local ovulation test example images in examples/opk/. That directory is gitignored except for a placeholder file, so you can drop private sample images there without polluting the repo.