zod-validation

Zod Validation (v4)

Type-safe schema validation for TypeScript. Zod v4 introduces top-level format functions, z.stringbool(), z.iso.* date formats, z.overwrite() transforms, z.file(), z.toJSONSchema(), getter-based recursive types, .meta(), and the unified error function.

Package: zod (also zod/mini for smaller bundles)

Quick Reference

Pattern	Usage
z.object({ ... })	Define object schemas
z.string(), z.number()	Primitive types
z.email(), z.url(), z.uuid()	Top-level string formats (v4)
z.iso.date(), z.iso.datetime()	ISO date/time formats (v4)
z.int(), z.float32(), z.int32()	Fixed-width number formats (v4)
z.templateLiteral([...])	Template literal type validation (v4)
z.enum([...]), z.literal()	Enums and literals
z.union([...]), z.discriminatedUnion()	Union types
z.array(), z.tuple()	Array and tuple types
z.record(), z.map()	Key-value collections
.optional(), .nullable()	Optional and nullable modifiers
.default(), .catch()	Default values and fallbacks
.prefault()	Pre-parse default (parsed through schema, v4)
z.coerce.number()	Type coercion before validation
z.stringbool()	String-to-boolean parsing (v4)
.transform(), .overwrite()	Output transforms
z.pipe()	Chain schemas (output feeds next input)
.refine(), .superRefine()	Custom validation logic
.parse(), .safeParse()	Validate and extract data
z.infer<typeof Schema>	Extract TypeScript type from schema
z.input<>, z.output<>	Input vs output types with transforms
z.file()	File instance validation (v4)
z.toJSONSchema()	Convert schema to JSON Schema (v4)
.meta(), .describe()	Attach metadata to schemas (v4)
z.prettifyError()	Human-readable error formatting (v4)
z.treeifyError()	Structured error tree (replaces .format(), v4)
z.registry()	Typed schema registry (v4)
{ error: (issue) => ... }	Unified error customization (v4)
Getter-based recursion	Recursive types without z.lazy() (v4)
z.globalRegistry	Global schema metadata registry (v4)
z.config(z.locales.en())	Internationalized error messages (v4)

Common Mistakes

Mistake	Fix
z.string().email()	z.email() (v4 top-level format)
z.string().url()	z.url() (v4 top-level format)
Using parse without try/catch	Use safeParse for error handling
Forgetting .optional()	Add when field may be undefined
z.any() for unknown data	Use z.unknown() for type-safe unknown
.transform() for same-type changes	Use .overwrite() (introspectable, v4)
Missing .min(1) on strings	Empty strings pass z.string() by default
z.number().parse(Infinity)	z.number() rejects Infinity in v4
z.number().safe() for floats	.safe() equals .int() in v4 (no floats)
z.lazy() for recursive types	Use getter syntax in v4 (retains object methods)
required_error / invalid_type_error	Use unified error function in v4
.refine(fn, (val) => ({ message }))	Function-as-second-arg overload removed; use .superRefine()
errorMap on schemas	Replaced by error function in v4
z.record(z.string()) single arg	v4 requires two args: z.record(z.string(), z.string())
.format() / .flatten() on ZodError	Deprecated; use z.treeifyError(err) in v4
.default() with input type value	v4 .default() uses output type; use .prefault() for input

Delegation

Use this skill for Zod schema definition, validation, parsing, type inference, coercion, error formatting, metadata, and JSON Schema conversion. For form integration, delegate to the tanstack-form skill.

References

• Schema Types — primitives, string formats, number formats, template literals, objects, arrays, enums, unions, records, optional, nullable
• Transforms and Parsing — coercion, stringbool, transforms, overwrite, pipe, refinements, parsing, type inference
• Error Handling — unified error function, prettifyError, treeifyError, ZodError, error formatting, internationalization
• Common Patterns — form validation, API responses, environment variables, schema composition, recursive types, branded types
• Metadata and JSON Schema — meta, describe, globalRegistry, toJSONSchema, file validation, Zod Mini