I guess I'm not clear on what you mean about putting business logic in the client. It can't only be on the client side. If you do so, then obviously you have to replicate it on the server to check that the client was sending the right results, no? Not to mention avoiding thread races and double inserts and whatever else may have gone stale on the server before you allow a client to validate something? Even if your code isn't public-facing, the server still needs to check everything. As a solo dev it seems insane to me to ever put business logic in the client, unless the client and server literally share the same typescript codebase for crosschecking ops, and even then the server needs the same code plus additional safeguards. It baffles me that anyone would write a platform from the ground up with primary business logic on the client side, if the server isn't written in the same language. Maybe some simple initial validations and checks to avoid bombarding the server, but the server has to be the central source of truth.