Systems and methods described herein, which utilize a combination of batch-processing and on-demand processing to provide recommendations, can include database(s) that store client data, item data, and executable code for composable algorithms that utilize the client data and/or the item data to provide recommendations. The system also includes a batch-process results data store that stores results of composable algorithms executed using batch-processing. Additionally, the system includes an algorithm engine that accepts calls to composable algorithms and output results thereof. The algorithm engine determines which called composable algorithms are designated as being executable using batch-processing, and which are designated as being executable using on-demand processing. The algorithm engine returns results of called composable algorithms designated as being executable using on-demand processing by executing the executable code thereof, and returns results of called composable algorithms designated as being executable using batch-demand-processing by obtaining the results from the batch-process results data store.