Floats

Currency analysis tool for exploring exchange rates, comparing multiple pairs, and viewing historical trends over time.

Check it here — full-featured live demo, deployed on Netlify

About

This project was initially made as a tool for my own daily use.

There are lots of finance apps out there, but none of them fully supported my workflow (which previously lived in a Google Sheets setup). Floats replaces this setup with a simpler and more effective experience.

I specifically made this project as a tool, not a product. There are no extra distractions, flashy alerts, and other dark patterns.

Features

• Support for 136 currencies (e.g., USD, EUR, CHF and more)
• Cross-rate calculation for any pair:
  • USD/EUR, NOK/JPY, AMD/UZS, and more
  • 18k options available (136 × 135 = 18 360)
• Historical data for about 26 years, updated daily
• Multiple pairs support to compare on chart and table
• Shareable URLs
• Interactive chart for any time range
• Data table for precise values
  • Select & copy cells as in Excel
• Light/Dark theme with auto-detect
• Mobile-friendly with PWA support

Technical Highlights

• URL-driven app state (selected currencies)
  • Why: enables deep linking, ability to share a view
• Dynamic cross-rate calculations for any pair (EUR pivot calculations)
  • Why: support for any currency pair, even without a direct rate
• Custom complex UI components:
  • Chip-based multiselect with autocomplete
  • Data table with virtual scrolling, cells range selection and clipboard integration
  • Why custom: this is intentional for learning depth (described here)
• FOUC-free theme switching (no light theme flash on reload)

See also: architecture decisions and specification.

Built With

• React v19 + React Router v7
• Zustand — state management
• Highcharts — chart
• Vite — bundling
• Vitest
  • Currently only calculation, store, and main hooks tests, ~70-85% coverage
  • Planning to set up Vite Browser Mode to test critical components and pages

Development

Clone repository:

git clone https://github.com/icmx/floats && cd floats

Install dependencies:

npm install

Run for development — navigate to localhost:5173/explore?by=USDEUR:

npm run dev

Also supported:

npm run lint
npm run test
npm run build

License

MIT.