Some use cases I think about off the top of my head: - Data model operations on local copy of data: For some use cases you can't just send everything to the se

Some use cases I think about off the top of my head: - Data model operations on local copy of data: For some use cases you can't just send everything to the server all the time, instead you want a local representation which is periodically synced with the server - Logging / monitoring: Expose a single logging / monitoring API which can be shared across platforms - Input validation / rules engine: Consider implementing a syntax highlighter, you wouldn't want to do that on the backend. Even simple form validation might sometimes be preferable to do client side, calling the multiplatform validate(data_model) and getting per-field validation back would allow for a lot of logic re-use. - Do work that could be done on the server: Because of a lot of factors, like privacy or cost you might want to do work that could be done on the server. I.e, calling some sensitive third party API (banking?) where you have to transform requests/responses. Or maybe computation on large sets of data (video compression?) which otherwise would need to be sent to the backend. - Interact with devices only locally accessible: IoT/bluetooth things