iFolio: a portfolio tracker that runs in your browser

Everything you see is calculated in the browser from your own transactions and public prices.

• An encrypted vault. The key comes from your passphrase (PBKDF2-HMAC-SHA256, 600,000 iterations), and the data is sealed with AES-256-GCM.
• Tax lots and cost basis. Open positions expand into their lots, with FIFO, LIFO, Specific ID and Average Cost, and a flag for wash sales.
• Imports and sync. Bank-specific CSV parsers for Schwab and Optum plus a generic one, with duplicates removed, and balances written to a Google Sheet through OAuth 2.0.
• Dashboard, positions and income. Value over time, allocation and monthly income, with filters by account and period.
• Installable and responsive. A PWA with dark mode, a collapsible sidebar on desktop and a bottom tab bar on phones.

Every number on screen is rebuilt from the raw transactions by one pure function, so positions, tax lots and income can’t drift apart. The code is TypeScript with no any, enforced in CI.

I first built a Schwab OAuth integration for market data, then switched to Yahoo Finance. That removed the sign-in to maintain and about 60% of the Worker code.

I built iFolio entirely through AI pair programming, with no team and no outsourcing.

• 224 sessions across 5 AI models. I began with careful prompt-by-prompt guidance, testing each feature as it landed.
• Several agents at once. Later one agent refactored the ledger engine while another built the charts and a third set up CI/CD, held together by typed interfaces.