We support the following types of currencies as both source and target currencies 

• FIAT: We support most traditional FIAT currencies (exchangeratesapi.io: Our API is integrated with a number of highly reputable foreign exchange rate sources, offering the most recent and accurate rates for 200+ pairs.)

• Coin: Native currencies of blockchains

• Token: Smart contract-based (ERC-20) tokens 

During the calculation of exchange rates, we use the following services.

For FIAT currencies, we use exchangeratesapi.io to query the exchange rates between the source and destination currencies.

For COIN currencies, we use cryptocompare.com to query the USD price of the COIN.

For TOKEN currencies, we use dexscreener.com to query the USD price of the TOKEN based on the swap pairs with the highest liquidity. 

•  Basically, during the exchange, we query the USD price as a reliable common point for both source and target currencies and calculate the result based on the exchange rate between something-USD and USD-something.

•  So, first, we convert the source currency to USD if it is not USD. If the source currency type is COIN, we query the USD price of the respective COIN from cryptocompare.com. If the source is TOKEN, we search for swap pairs on dexscreener.com where the source TOKEN is on one side, and we take the USD exchange rate from among those pairs with the highest liquidity. If the source is a FIAT currency different from USD, we query the exchange rate for the source FIAT from exchangeratesapi.io. 

•  We apply the same logic for the target currency, so we get the exchange rate in USD for both the source and the target currencies, and then calculate the result from these.