Guide · Open source
How to use Zod: schema validation with TypeScript types
Updated · written with AI from the project's own documentation and checked against our catalogue data
Zod is a TypeScript library for defining schemas that check whether data has the expected shape, such as form input or API responses. This guide explains what Zod does, what you need before starting, and where it fits in a TypeScript project. By the end you will understand the one-schema approach and know the first steps to take.
Zodcolinhacks/zod · ★ 44.2k · MIT Install options & downloads Quick start
- 1Check prerequisites. Make sure Node.js and TypeScript are available in your project.
- 2Install the package. Add Zod with your package manager. The README excerpt is truncated, so confirm the exact command on zod.dev.
- 3Define a schema. Describe the shape of the data you expect, such as a form submission or an API response.
- 4Validate incoming data. Check values against the schema at runtime before your code uses them.
- 5Use the inferred type. Use the TypeScript type that Zod derives from the schema in the rest of your code.
- 6Read the docs. Go to zod.dev for the full API and setup details not covered in the README excerpt.
What does Zod do?
You describe the shape of your data once as a schema. Zod then validates values at runtime, so you can check that incoming data really matches the shape you expect.
Zod also gives you a TypeScript type that matches the schema, so you do not have to write a separate type and validator for the same data.
What do you need before installing Zod?
The listed prerequisites are Node.js and TypeScript. Zod is described as TypeScript-first, so this guide assumes a TypeScript project.
The project's install method is a package manager. The README excerpt available here is truncated and only points to the package, so check the homepage at zod.dev for full setup details.
- Node.js
- TypeScript
git clone https://github.com/colinhacks/zodHow do you define a schema once for data and types?
Write a schema that describes the shape your data should have, such as the fields a form submits or the fields an API returns. Use that single definition both for runtime checks and for the static type in your code.
Keeping one definition avoids the common problem of a type and a validator drifting apart over time.
How do you validate API requests and responses with Zod?
Teams use Zod to validate API request and response data in TypeScript projects. Validate data where it enters your code, then rely on the inferred type for everything after that point.
The source does not include detailed API examples, so refer to zod.dev for the exact methods to call.
How do you use Zod for form input?
Form input is one of the examples the library is meant for. Define a schema for the fields a form collects, check the submitted values against it, and use the inferred type for the validated data.
Zod is a code library, so you write the schema yourself. It is not a visual or no-code tool.
When should you pick Zod over other libraries?
Zod is a good fit for TypeScript developers who want runtime checks that match their static types. The project lists Yup, io-ts, Joi and Valibot as comparable projects.
The README excerpt does not compare these libraries, so test a small schema in each candidate before you commit.
- Yup
- io-ts
- Joi
- Valibot
What people use it for
- Validating request bodies in a TypeScript API
- Checking API responses before the rest of the app uses them
- Validating form input against a schema
- Keeping one definition for both runtime validation and static types
Frequently asked questions
Is Zod free to use?
Zod is released under the MIT licence, as listed on its repository. Read the licence file in the project for the full terms.
What do I need to install Zod?
The listed prerequisites are Node.js and TypeScript. The project uses a package manager for installation, and the full setup steps are on zod.dev.
Can I use Zod without TypeScript?
Zod is described as TypeScript-first, and the README excerpt gives no JavaScript-only guidance. Check zod.dev before using it in a plain JavaScript project.
What are alternatives to Zod?
The project lists Yup, io-ts, Joi and Valibot as comparable projects. Each one is a candidate to test against your own schemas.
Why is my Zod validation failing?
The README excerpt does not cover troubleshooting. Compare your schema with the examples in the full documentation at zod.dev and check that the data shape matches what you defined.
How does Zod compare to Yup or Joi?
The source does not include a feature comparison. Both are listed as comparable projects, so build a small schema in each and compare the result for your use case.
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Our verdict
Zod suits TypeScript developers who want runtime checks that match their static types, especially for API data and form input. If your project does not use TypeScript, or you need a no-code tool, pick something else.
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