Fees and foreign currency exchange calculation

A system comprising:

• a communication interface configured to receive a fee calculation request linked to an online financial transaction associated with a fee type, a country code, and a client identifier;
• a database configured to store a plurality of overriding base fees each linked to a client identifier, and a plurality of default base fees each linked to a fee type and a country code;
• a data cache comprising at least one writer view and at least one reader view identified by control;
• a non-transitory memory storing machine-readable instructions;
• and
• a processor communicatively coupled to the communication interface, the database, and the data cache, wherein the processor is configured to read instructions from the non-transitory memory to cause the system to perform operations comprising:
• extracting fee calculation data from the database into the data cache, wherein the at least one writer view stores the extracted fee calculation data;
• swapping the at least one writer view with the at least one reader view by updating the control data, wherein the extracting and the swapping are periodically performed to refresh the data cache;
• determining a current reader view based on the control data;
• accessing, using the client identifier, the current reader view to determine whether a default fee or an overriding fee applies to the online transaction;
• retrieving, from the current reader view based on the fee type and the country code, the default fee to use as a base fee in response to determining that the default fee applies;
• calculating a transaction fee for the online transaction based at least in part on the base fee;
• determining whether the current reader view has changed due to the periodic performing of the extracting and the swapping;
• transmitting, via the communication interface, in response to the determining that the current reader view has not changed, a fee calculation response indicative of the calculated transaction fee;
• and
• repeating the accessing, the retrieving, and the calculating in response to determining that the current reader view has changed.