Basically joi (https://joi.dev/api/?v=17.13.3) but different in some way?
Personally I use zod in my API for body validations, it's super nice to write the schema then just use `type Body = z.infer(schema)` to get the TS type to use inside the code.
not really "instead", more like "in addition to". Even if your code compiles, if you are receiving data, e.g., via API, then you need to check that it actually conforms to the type/schema you expect. What is run is JS, so it, sadly, won't just crash/error if an object that is supposed to be of `type Cat = {name: string, ownerId: number}` lacks an `ownerId` at runtime.
Have you used Pydantic in Python? It's like that, but feels worse, IMO lol. I say this because Pydantic fits into writing Python code much more naturally than writing Zod stuff fits into writing TypeScript, IMO.
The main distinction is that ZOD allows you to extract a TypeScript type from your schema. This means you get both compile-time and run-time type checking.
Typescript is build-time validation, but in the end TS is "just JS"
Zod provides runtime validation (and also works well with TS)