Valibot vs Zod: Schema Validation Library Comparison

Schema validation is essential for type-safe JavaScript applications. Zod has been the dominant validation library, but Valibot offers a new approach with modularity and bundle size optimization. This guide compares both libraries to help you choose the right validation solution for your project.

Key Takeaways

Library Overview

What is Valibot?

Valibot is a modular schema validation library built with bundle size in mind. Created by Fabian Hiller in 2023, it takes a functional approach to validation. Instead of a chainable API, Valibot uses composable functions that can be tree-shaken, resulting in minimal bundle impact.

What is Zod?

Zod is a TypeScript-first schema validation and static type inference library. Created by Colin McDonnell in 2020, it has become the standard for schema validation in the TypeScript ecosystem. Zod uses a fluent, chainable API that makes schema definitions intuitive and readable.

Bundle Size Comparison

One of Valibot's main selling points is its modular architecture:

API Style Comparison

Different approaches to defining schemas:

Valibot

// Valibot - Functional approach
import * as v from 'valibot'

// String schema
const StringSchema = v.string()

// Object schema
const UserSchema = v.object({
  name: v.string(),
  email: v.pipe(v.string(), v.email()),
  age: v.optional(v.number()),
})

// Array schema
const UsersSchema = v.array(UserSchema)

// Validation
const result = v.safeParse(UserSchema, {
  name: 'John',
  email: 'john@example.com',
  age: 30,
})

if (result.success) {
  console.log(result.output) // Typed as { name: string, email: string, age?: number }
} else {
  console.log(result.issues)
}

Zod

// Zod - Chainable approach
import { z } from 'zod'

// String schema
const StringSchema = z.string()

// Object schema
const UserSchema = z.object({
  name: z.string(),
  email: z.string().email(),
  age: z.number().optional(),
})

// Array schema
const UsersSchema = z.array(UserSchema)

// Validation
const result = UserSchema.safeParse({
  name: 'John',
  email: 'john@example.com',
  age: 30,
})

if (result.success) {
  console.log(result.data) // Typed as { name: string, email: string, age?: number }
} else {
  console.log(result.error)
}

Feature Comparison

Comparing capabilities across key areas:

Ecosystem and Integrations

Available integrations and community support:

When to Use Each Library

Conclusion

Both Valibot and Zod are excellent schema validation libraries that provide type-safe development. Valibot's modular approach is innovative and delivers on its promise of smaller bundle sizes, making it ideal for performance-conscious applications. Zod's maturity, ecosystem, and familiar chainable API make it the safe default for most projects. The good news is that both libraries produce standard output that can be easily converted, making it possible to start with one and migrate to the other if needed.

FAQ