ForexRadar

Track historical Visa, Mastercard, and ECB exchange rates with real markup data.

Live Demo

About

When you use your credit card abroad, Visa and Mastercard apply their own exchange rates, often with hidden markups over the interbank rate. ForexRadar shows you exactly what those rates are, how they compare to the ECB reference rate, and how they've changed over time.

Features

• Compare Visa, Mastercard, and ECB rates side-by-side on interactive charts
• View up to 365+ days of historical data for archived currency pairs
• See Visa's actual markup percentage over ECB mid-market rates
• Offline-first with local caching for fast repeat visits
• Share specific currency pairs via URL
• Dark and light themes

How It Works

Exchange rates are fetched twice daily (at 17:00 and 23:00 UTC) and stored as CSV files. The frontend loads data progressively: first from local cache, then from the server archive, and finally from live APIs for the most recent rates.

Getting Started

Prerequisites

• Bun >= 1.3.5

Installation

git clone https://github.com/avishj/ForexRadar.git
cd ForexRadar
bun install

Usage

Fetch the latest exchange rates:

bun run daily

Then open index.html in your browser.

Backfilling Historical Data

To populate historical data for all currency pairs:

bun run backfill        # Visa and Mastercard
bun run ecb-backfill    # ECB rates

Development

Commands

Command	Description
bun run daily	Fetch latest rates
bun run backfill	Populate historical data
bun run validate	Validate CSV data integrity
bun run check	TypeScript type checking
bun run lint	Run ESLint
bun run test	Run smoke tests
bun run test:unit	Run unit tests
bun run test:e2e	Run end-to-end tests
bun run test:all	Run all tests

Project Structure

ForexRadar/
├── backend/          # Data fetching scripts
├── js/               # Frontend modules
├── shared/           # Shared utilities
├── tests/            # Test suites
├── db/               # CSV data storage
└── css/              # Stylesheets

Data Sources

• Visa - Card network exchange rates with markup percentages
• Mastercard - Card network exchange rates
• ECB - European Central Bank daily reference rates

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feat/amazing-feature)
3. Make your changes
4. Run bun run check && bun run lint && bun run test:all to verify
5. Commit with a conventional commit message (feat: add amazing feature)
6. Push and open a Pull Request

License

AGPL-3.0-only