There are 2 repositories under currency-converter-php topic.
Exchange rates/Currency Converter Library for PHP
Standardized wrapper for popular currency rate APIs. Currently supports FixerIO, CurrencyLayer, Open Exchange Rates and Exchange Rates API.
Convert-Currencies PHP All currency conversion included
Currency Converter Package
Laravel package for working with api.alfaexchange.io API service
TCMB Kur Çevirici/Currency Converter with PHP
the php wrapper of openexchangerates
This is a simple web application for converting currencies