Comparison with Other Validation Libraries

Zod offers several unique advantages compared to other popular validation libraries.

Zod vs Yup

Type Inference

// Zod
const userSchema = z.object({
  name: z.string(),
  age: z.number(),
});
type User = z.infer<typeof userSchema>; // Perfect type inference

// Yup
const yupSchema = yup.object({
  name: yup.string(),
  age: yup.number(),
});
// Requires manual type definition or less precise inference

Default Value Handling

// Zod - Explicit default value handling
const zodSchema = z.object({
  name: z.string(),
  age: z.number().default(18),
});

// Yup - More lenient default handling
const yupSchema = yup.object({
  name: yup.string(),
  age: yup.number().default(18),
});

Performance Comparison

// Zod - Faster validation
const zodResult = userSchema.safeParse(data);

// Yup - Relatively slower
const yupResult = await yupSchema.validate(data);

Zod vs Joi

Type Safety

// Zod - Fully type-safe
const zodSchema = z.object({
  email: z.string().email(),
  age: z.number().min(0),
});

// Joi - No built-in type inference
const joiSchema = Joi.object({
  email: Joi.string().email(),
  age: Joi.number().min(0),
});

API Style

// Zod - Chainable API, modern syntax
const zodSchema = z.string()
  .min(3)
  .max(20)
  .email();

// Joi - Traditional validation API
const joiSchema = Joi.string()
  .min(3)
  .max(20)
  .email();

Zod vs class-validator

Decorators vs Schema

// Zod - Declarative schema
const UserSchema = z.object({
  @IsEmail()
  email: z.string().email(),
  
  @Min(0)
  age: z.number().min(0),
});

// class-validator - Decorator-based
class User {
  @IsEmail()
  email: string;

  @Min(0)
  age: number;
}

Runtime Validation

// Zod - Direct validation
const result = UserSchema.safeParse(data);

// class-validator - Requires instantiation
const user = new User();
Object.assign(user, data);
const errors = await validate(user);

Zod's Advantages

1. Type Safety

// Zod automatically infers types
const schema = z.object({
  name: z.string(),
  age: z.number().optional(),
});

type Person = z.infer<typeof schema>;
// Automatically inferred as:
// {
//   name: string;
//   age?: number;
// }

2. Zero Dependencies

// package.json
{
  "dependencies": {
    "zod": "^3.0.0"
    // No other dependencies needed
  }
}

3. Rich API

const schema = z.object({
  id: z.string().uuid(),
  email: z.string().email(),
  website: z.string().url().optional(),
  age: z.number().int().min(0).max(120),
  birthDate: z.date(),
  tags: z.array(z.string()).nonempty(),
});

4. Extensibility

// Custom validator
const passwordSchema = z.string().refine(
  (password) => {
    // Custom password validation logic
    return password.length >= 8 &&
           /[A-Z]/.test(password) &&
           /[a-z]/.test(password) &&
           /[0-9]/.test(password);
  },
  {
    message: "Password must contain uppercase, lowercase, number, and be at least 8 characters",
  }
);

5. Transform Capabilities

const schema = z.string()
  .transform(s => s.toLowerCase())
  .transform(s => s.trim())
  .refine(s => s.length > 0, "String cannot be empty");

const result = schema.parse("  HELLO  ");
// Result: "hello"