Zod

TypeScript-first schema validation with static type inference
by @colinhacks

Docs • Discord • 𝕏 • Bluesky

### [Read the docs →](https://zod.dev/api)

## What is Zod? Zod is a TypeScript-first validation library. Define a schema and parse some data with it. You'll get back a strongly typed, validated result. ```ts import * as z from "zod"; const User = z.object({ name: z.string(), }); // some untrusted data... const input = { /* stuff */ }; // the parsed result is validated and type safe! const data = User.parse(input); // so you can use it with confidence :) console.log(data.name); ```
## Features - Zero external dependencies - Works in Node.js and all modern browsers - Tiny: `2kb` core bundle (gzipped) - Immutable API: methods return a new instance - Concise interface - Works with TypeScript and plain JS - Built-in JSON Schema conversion - Extensive ecosystem
## Installation ```sh npm install zod ```
## Basic usage Before you can do anything else, you need to define a schema. For the purposes of this guide, we'll use a simple object schema. ```ts import * as z from "zod"; const Player = z.object({ username: z.string(), xp: z.number(), }); ``` ### Parsing data Given any Zod schema, use `.parse` to validate an input. If it's valid, Zod returns a strongly-typed _deep clone_ of the input. ```ts Player.parse({ username: "billie", xp: 100 }); // => returns { username: "billie", xp: 100 } ``` **Note** — If your schema uses certain asynchronous APIs like `async` [refinements](https://zod.dev/api#refinements) or [transforms](https://zod.dev/api#transforms), you'll need to use the `.parseAsync()` method instead. ```ts const schema = z.string().refine(async (val) => val.length <= 8); await schema.parseAsync("hello"); // => "hello" ``` ### Handling errors When validation fails, the `.parse()` method will throw a `ZodError` instance with granular information about the validation issues. ```ts try { Player.parse({ username: 42, xp: "100" }); } catch (err) { if (err instanceof z.ZodError) { err.issues; /* [ { expected: 'string', code: 'invalid_type', path: [ 'username' ], message: 'Invalid input: expected string' }, { expected: 'number', code: 'invalid_type', path: [ 'xp' ], message: 'Invalid input: expected number' } ] */ } } ``` To avoid a `try/catch` block, you can use the `.safeParse()` method to get back a plain result object containing either the successfully parsed data or a `ZodError`. The result type is a [discriminated union](https://www.typescriptlang.org/docs/handbook/2/narrowing.html#discriminated-unions), so you can handle both cases conveniently. ```ts const result = Player.safeParse({ username: 42, xp: "100" }); if (!result.success) { result.error; // ZodError instance } else { result.data; // { username: string; xp: number } } ``` **Note** — If your schema uses certain asynchronous APIs like `async` [refinements](https://zod.dev/api#refinements) or [transforms](https://zod.dev/api#transforms), you'll need to use the `.safeParseAsync()` method instead. ```ts const schema = z.string().refine(async (val) => val.length <= 8); await schema.safeParseAsync("hello"); // => { success: true; data: "hello" } ``` ### Inferring types Zod infers a static type from your schema definitions. You can extract this type with the `z.infer<>` utility and use it however you like. ```ts const Player = z.object({ username: z.string(), xp: z.number(), }); // extract the inferred type type Player = z.infer; // use it in your code const player: Player = { username: "billie", xp: 100 }; ``` In some cases, the input & output types of a schema can diverge. For instance, the `.transform()` API can convert the input from one type to another. In these cases, you can extract the input and output types independently: ```ts const mySchema = z.string().transform((val) => val.length); type MySchemaIn = z.input; // => string type MySchemaOut = z.output; // equivalent to z.infer // number ```