An API makes sense for this case when you won't be throwing away a lot of the raw data in favor of the processed/transformed data. But doing a lot of these ope

An API makes sense for this case when you won't be throwing away a lot of the raw data in favor of the processed/transformed data. But doing a lot of these operations on-server makes sense when there's a significant volume of highly parallelizable transformations which need to be done on the data before it's usable. Of course the best solution is likely to be a happy medium between the two, where simple low-level transformations are done on-server and the rest of the data preparation is done as the data is transferred to the client.