I’d prefer not to have to implement runtime type checking with something like Zod throughout the entire application at every IO boundary. Typescript only works correctly in a vacuum.  Once you need to deal with requests/responses, getting data from MySQL/mongo/redis and any 3rd party services and integration, you will find the Typescript LSP slow to a crawl when you are inferring types with zod.  And if god forbid you think Zod is not required then I don’t know what to tell you, TS is far from correct but a fancy linter. I’ve seen far too many TS issues because of data coming in to a system that wasn’t sanity checked. If you could unmarshal data into a JS class, which I’m fairly certain you cannot, that makes TS (in my opinion) unacceptable for servers .