Json-Schema-to-Zod

A package to convert JSON schema (draft 4+) objects into Zod schemas in the form of Zod objects at runtime.

A fork of @n8n/json-schema-to-zod with improved ESM module compatibility.
The src files are of Jun 21, 2025 (version 1.3.0, commit hash: 351db43).

Installation

npm install @h1deya/json-schema-to-zod

Usage

import { jsonSchemaToZod } from '@h1deya/json-schema-to-zod';
import { z } from 'zod';

const schema = {
  type: 'object',
  properties: {
    name: { type: 'string' },
    age: { type: 'number' }
  },
  required: ['name']
};

const zodSchema = jsonSchemaToZod(schema);

// Validate data
const validData = { name: 'John', age: 30 };
zodSchema.parse(validData); // Works!

const invalidData = { age: 30 };
try {
  zodSchema.parse(invalidData);
} catch (error) {
  console.error(error); // Validation error: name is required
}

The Problem This Fork Solves

When using the original @n8n/json-schema-to-zod package in an ESM environment (projects with "type": "module" in package.json), you might encounter this error:

Error [ERR_MODULE_NOT_FOUND]: Cannot find module '.../parse-schema' imported from '.../json-schema-to-zod.js'

This happens because:

1. Node.js requires file extensions (like .js) in ESM import paths
2. The original package's TypeScript source doesn't include these extensions
3. When compiled for ESM, this creates broken imports

How This Fork Fixes It

This fork fixes the issue through a specialized build process that:

1. Temporarily adds .js extensions to all imports in the TypeScript source
2. Compiles the modified source to ESM
3. Restores the original source code afterward

This approach:

• Preserves the original source code (making future upstream syncs easier)
• Produces ESM-compatible output that works in modern Node.js environments
• Maintains full functionality and API compatibility

Additional Fix: CommonJS Require Removal

A leftover CommonJS require() usage was found in src/parsers/parse-nullable.ts and was replaced with an ESM import:

--- a/src/parsers/parse-nullable.ts
+++ b/src/parsers/parse-nullable.ts
@@ -1,9 +1,9 @@
 import { z } from 'zod';
 
 import type { JsonSchemaObject } from '../types';
+import { parseSchema } from './parse-schema';
 
 export const parseNullable = (jsonSchema: JsonSchemaObject & { nullable: true }, refs: any) => {
-       const { parseSchema } = require('./parse-schema');

Source & Maintenance

This package is based on the original code from:

• Repository: n8n
• Commit Hash: 351db43 (Jun 21, 2025)
• Source Path: packages/@n8n/json-schema-to-zod

To update with upstream changes:

1. Update the source files in the src directory
2. Run npm run build
3. Test with npm test

Credits

Original package created by Stefan Terdell and the n8n team.

This fork maintains the original ISC license and acknowledges all original contributors.

License

ISC License