PTAX

A currency converter backed by the Brazilian Central Bank (BCB) PTAX closing rates.

Installation

def deps do
  [
    {:ptax, "~> 2.0"}
  ]
end

Configuration

PTAX integrates with ex_money's exchange rate system. Add it to your config:

# config/config.exs
config :ex_money, api_module: PTAX.ExchangeRates

Usage

Convert using the latest known rates

iex> PTAX.exchange(Money.new!(:USD, "100"), :BRL)
{:ok, Money.new!(:BRL, "506.48")}

Convert using rates for a specific date

iex> PTAX.exchange(Money.new!(:GBP, "50"), :BRL, ~D[2026-05-15])
{:ok, Money.new!(:BRL, "337.60")}

Dates with no BCB data (weekends, holidays) return {:error, {Money.ExchangeRateError, "404"}}. The latest-rates lookup automatically walks back up to 7 days to find the most recent available data.

See also

PTAX only provides the rate source. For richer operations, use ex_money directly:

• Money.to_currency/2,3 — convert between any two currencies
• Money.cross_rate/2 — derive a cross rate between two currencies
• Money.ExchangeRates — access and configure the exchange rate backend