currencyconverter

A simple CLI tool written in Go for calculating exchange rates using foreign exchange reference rates published by the European Central Bank.

Installation

Go install

go install github.com/timorunge/currencyconverter/cmd/currencyconverter@latest

Binary download

Download pre-built binaries for your platform from the releases page.

Build from source

git clone https://github.com/timorunge/currencyconverter.git
cd currencyconverter
make build

Quick Start

Convert 100 EUR to USD:

currencyconverter --amount 100 --from EUR --to USD

100 EUR ≈ 111.51 USD (2019-07-31, ECB)

Convert for a specific date:

currencyconverter --amount 500 --from USD --to GBP --date 2019-07-31

Swap currencies with --reverse:

currencyconverter --from EUR --to USD --reverse

Get JSON output:

currencyconverter --amount 100 --from EUR --to USD --json

{"amount":100,"from":"EUR","to":"USD","result":111.51,"date":"2019-07-31","source":"ECB"}

Usage

currencyconverter - Exchange rate calculator using ECB reference rates

Usage:
  currencyconverter [OPTIONS]

Options:
  -f, --from string            Currency to use as base (default "EUR")
  -t, --to string              Currency to convert to (default "USD")
  -a, --amount float           Amount to calculate (default 1)
  -d, --date string            Date for the calculation (latest|YYYY-MM-DD) (default "latest")
  -r, --reverse                Swap from and to values
      --json                   Output result as JSON
      --no-cache               Disable caching
  -h, --help                   Show this help message
      --version                Show the version of currencyconverter
      --supported-currencies   Show a list with all supported currencies

Supported Currencies

AUD, BGN, BRL, CAD, CHF, CNY, CZK, DKK, EUR, GBP, HKD, HUF, IDR, ILS, INR, ISK, JPY, KRW, MXN, MYR, NOK, NZD, PHP, PLN, RON, SEK, SGD, THB, TRY, USD, ZAR

Run currencyconverter --supported-currencies for the full list.

Caching

Exchange rates are cached locally as JSON files in the OS temp directory. Latest rates are cached until the top of the next hour, keeping network calls low while staying current with ECB updates. Historical dates are cached indefinitely since their rates never change. Disable caching with --no-cache.

Development

make help     # Show all available targets
make check    # Run all quality gates (fmt, tidy, vet, lint, test)
make lint     # Run golangci-lint
make test     # Run tests with race detector
make build    # Build static binary

License

BSD 3-Clause "New" or "Revised" License