How to make JSON Marshal in Go output keys in lowercase?

Hi everyone! I'm writing my first REST API in Go and ran into a problem: when serializing a struct to JSON via `json.Marshal`, all fields are output with capital letters because exported fields in Go start with a capital letter. For example: ```go type User struct { Name string Email string Age int } func main() { u := User{"Ivan", "ivan@example.com", 30} data, _ := json.Marshal(u) fmt.Println(string(data)) // Output: {"Name":"Ivan","Email":"ivan@example.com","Age":30} } ``` But on the frontend (React), everyone expects keys in camelCase or snake_case: `name`, `email`, `age`. I tried writing my own marshaller, but that's too cumbersome for a project with 20+ structs. I've read about `json:"name"` tags, but manually writing them for each field — that's