In one aspect, the present disclosure relates to a system for improved transactional mainframes, the system comprising a processor, a database, an application programming interface (API) module, and a transaction import module. The API module can be configured to: receive transaction data comprising a transaction type, a user identifier, one or more transaction card identifiers, and one or more fields associated with the transaction card identifiers; validate the transaction data using one or more of the stored validation rules associated with the one or more transaction card identifiers; generate one or more transaction cards; and store the transaction data and transaction cards to the database. The transaction import module can be configured to submit the transaction cards to the mainframe, view the status of submitted records, and enable retrying of transaction cards that failed to process.