zod-validation

You can validate API request bodies by defining a Zod schema and parsing incoming data, returning a 400 status with flattened validation errors if parsing fails. This enforces type-safe input boundaries to prevent invalid data from entering your application.

Type-safe parsing with Zod uses the z.infer operator to automatically derive TypeScript types directly from your validation schemas. This provides end-to-end type safety, ensuring your application code matches your runtime validation rules.

Validating environment variables uses Zod schemas to parse and check process.env at application startup. This ensures all required variables are present and correctly typed, providing robust startup checks that prevent runtime errors from missing configuration.

Yes, Zod schemas can be converted to JSON Schema using the zod-to-json-schema utility. This enables seamless Fastify schema integration and OpenAPI documentation generation while maintaining a single source of truth for validation.

Zod handles cross-field checks and data transformations using synchronous and asynchronous refinements. You can apply coercion to transform input types, ensuring complex validation logic across multiple fields executes correctly.

When input validation fails, safeParse returns an error object instead of throwing. You can extract flattened error outputs from this result to return user-friendly, structured validation messages in your API responses.