TypeScript Zod schema validation

Runtime validation of API responses, form data, or config requires manual type guards that drift from TypeScript types.

Use Zod for runtime validation with automatic type inference:

import { z } from 'zod';

const UserSchema = z.object({
id: z.string().uuid(),
name: z.string().min(1).max(100),
email: z.string().email(),
age: z.number().int().min(0).max(150).optional(),
role: z.enum(['admin', 'user', 'viewer']),
tags: z.array(z.string()).default([]),
});

// Type is automatically inferred
type User = z.infer<typeof UserSchema>;

// Validate and parse
const result = UserSchema.safeParse(apiResponse);
if (result.success) {
const user: User = result.data; // fully typed
} else {
console.error(result.error.issues);
}

// Transform during parsing
const NormalizedUser = UserSchema.transform(u => ({
...u,
email: u.email.toLowerCase(),
}));

Zod provides a single source of truth for both TypeScript types and runtime validation, eliminating type/validation drift.