Use shortcodes [exchange-rates] and [exchange-history] in any part of a page to call plugin interface.
Due to the limitations of the CoinMarketCap free API plan, only BTC conversion is available and only 100 currencies, but the plugin makes it easy to enable the conversion of all currencies with a little code refinement.
The plugin interface contains minimal design, but it is easy to customize using CSS for the tasks of a particular project.
This is very basic plugin implementation. No external libraries (CSS, JS, etc. ) used in this plugin.