zod-to-json-schema

What is zod-to-json-schema?

The zod-to-json-schema npm package is a utility that converts Zod schemas to JSON Schema. This is useful for generating JSON Schema definitions from Zod validation schemas, which can then be used for various purposes such as API documentation, validation, and more.

What are zod-to-json-schema's main functionalities?

Basic Schema Conversion

This feature allows you to convert a basic Zod schema to a JSON Schema. The example demonstrates converting a Zod object schema with string and integer properties to its JSON Schema equivalent.

const { z } = require('zod');
const { zodToJsonSchema } = require('zod-to-json-schema');

const schema = z.object({
  name: z.string(),
  age: z.number().int(),
});

const jsonSchema = zodToJsonSchema(schema);
console.log(JSON.stringify(jsonSchema, null, 2));

Nested Schema Conversion

This feature supports the conversion of nested Zod schemas to JSON Schema. The example shows a user schema that includes an address schema, demonstrating how nested objects are handled.

const { z } = require('zod');
const { zodToJsonSchema } = require('zod-to-json-schema');

const addressSchema = z.object({
  street: z.string(),
  city: z.string(),
});

const userSchema = z.object({
  name: z.string(),
  address: addressSchema,
});

const jsonSchema = zodToJsonSchema(userSchema);
console.log(JSON.stringify(jsonSchema, null, 2));

Array Schema Conversion

This feature allows for the conversion of Zod schemas that include arrays to JSON Schema. The example demonstrates converting a schema with an array of strings.

const { z } = require('zod');
const { zodToJsonSchema } = require('zod-to-json-schema');

const schema = z.object({
  tags: z.array(z.string()),
});

const jsonSchema = zodToJsonSchema(schema);
console.log(JSON.stringify(jsonSchema, null, 2));

Other packages similar to zod-to-json-schema

ajv

AJV (Another JSON Schema Validator) is a popular JSON Schema validator. While it focuses on validating JSON data against JSON Schema, it also provides utilities for generating JSON Schema from various sources. Compared to zod-to-json-schema, AJV is more focused on validation rather than schema conversion.

json-schema-to-typescript

This package converts JSON Schema to TypeScript types. While it operates in the opposite direction of zod-to-json-schema, it serves a similar purpose of bridging the gap between JSON Schema and TypeScript. It is useful for generating TypeScript definitions from existing JSON Schemas.

typescript-json-schema

This package generates JSON Schema from TypeScript types. It is similar to zod-to-json-schema in that it converts type definitions to JSON Schema, but it works directly with TypeScript types instead of Zod schemas.

README

Zod to Json Schema

Does what it says on the tin! Supports all relevant schema types as well as basic string, number and array length validations.

String pattern validation (ie email, regexp etc) is not available since Zod doesn't seem to expose the regexp source in any way I can find. Perhaps in later versions, though!

Usage:

import * as z from 'zod';
import toJsonSchema from 'zod-to-json-schema';

const mySchema = z.object({
  myString: z.string().min(5),
  myUnion: z.union([z.number(), z.boolean()]),
});

const jsonSchema = toJsonSchema(mySchema, 'mySchema');

Expected output:

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$ref": "#/definitions/mySchema",
  "definitions": {
    "mySchema": {
      "type": "object",
      "properties": {
        "myString": {
          "type": "string",
          "minLength": 5
        },
        "myUnion": {
          "type": ["number", "boolean"]
        }
      },
      "additionalProperties": false,
      "required": ["myString", "myUnion"]
    }
  }
}

Disclaimer

Once I'm satisfied that this package has reached parity with Zod I will keep the major versions in lockstep with that, possibly with simultaneous minor versions of both majors 1 and 3 (zod 2 was deprecated before leaving beta). As for now though (meaning major 0 for this package), expect breaking changes to the api to appear without notice.