After a year of active development, Zod 4 is officially released with major improvements. This stable version is faster, slimmer, and more TypeScript-optimized compared to the previous Zod 3.

Highlights of Zod 4

🚀 Outstanding Performance

• 14x faster string parsing: Deep optimizations in string validation make your app respond much faster, especially when handling large amounts of text data.
• 7x faster array parsing: Efficiently process complex or large arrays, minimizing latency in data validation.
• 6.5x faster object parsing: Ideal for objects with many fields, ensuring smoother validation and faster API responses.

⚡ TypeScript Compiler Optimization

• Reduces type instantiations by up to 100x, speeding up the TypeScript compiler significantly, especially for large and complex codebases.
• Compilation time is improved by around 10x compared to Zod 3, providing a smoother developer experience and faster editor feedback.

📦 Reduced Bundle Size

• Core bundle size is 2.3x smaller than Zod 3, making your applications lighter and faster to load.
• The zod/v4-mini variant is even lighter (~1.88KB gzip), using a functional API optimized for tree-shaking, perfect for projects with strict bundle size limits.

🏷️ Powerful Metadata System

• Allows attaching strongly-typed metadata to schemas, enabling easy mapping to standard JSON Schema.
• Great for automation tools, API documentation, and data transformation workflows.

🔄 Simple Recursive and Mutually Recursive Types

• Define self-referencing or mutually referencing types (e.g., category trees, user-post relationships) directly without complex casting hacks.
• Increases code clarity and maintainability.

🌐 Internationalized Error API

• Supports a locales system to translate error messages into multiple languages, improving user experience in global applications.
• English locale available now, with community contributions expected for more languages.

✨ New Top-Level String Format APIs

• Popular formats like email(), uuid(), ip(), and url() are now top-level functions, leading to cleaner code and better tree-shaking.
• Older method-based APIs on strings remain available but are deprecated.

🔤 z.stringbool()

• Converts strings to booleans using a flexible, environment-variable style (e.g., "true", "yes", "1" → true; "false", "no", "0" → false).
• Customizable truthy/falsy values to fit your specific needs, making it easy to validate boolean-like string inputs.

🎯 Simplified Error Customization API

• Unifies various error customization approaches into a single error parameter, which can be a string or function, enabling concise and clear error definitions.
• Reduces complexity and confusion when writing validations and handling errors.

🔀 More Powerful Discriminated Unions

• Supports multiple schema types as discriminators, including unions, pipes, and nested objects.
• Allows creating complex and maintainable type classifications for diverse data structures.

🔧 .overwrite() Method

• Alternative to .transform() for applying data transformations without changing the inferred type, preserving type information.
• Useful for simple data manipulation without breaking compatibility with JSON Schema or inferred types.

🧩 Zod Mini

• A super lightweight functional API variant that removes excess methods to optimize tree-shaking, resulting in very small final bundles.
• Perfect for front-end apps needing minimal download sizes while still using Zod for validation.

🚀 Conclusion

Zod 4 marks a significant advancement in TypeScript schema validation, offering enhanced performance, reduced bundle sizes, and a more intuitive API. With features like improved TypeScript compiler efficiency, a powerful metadata system, and streamlined error handling, Zod 4 is designed to meet the needs of modern development.

For comprehensive documentation, including guides on defining schemas, customizing errors, and integrating with JSON Schema, visit the official Zod 4 documentation: https://zod.dev/v4.

Happy coding! 😊