Headline: Zod 4 is a rewrite of the TypeScript-first schema validation library, released as the stable major in 2025. Four changes hit my code directly: string formats moved to top-level functions ( z. email() instead of z.
Source: [Dev.to](https://dev.to/ahmed_mahmoud360/what-changed-in-zod-4-and-how-i-migrated-production-schemas-di0)