JSON Schema $Ref Parser

Parse, Resolve, and Dereference JSON Schema $ref pointers

Installation

Install using npm:

npm install @hey-api/json-schema-ref-parser
yarn add @hey-api/json-schema-ref-parser
bun add @hey-api/json-schema-ref-parser

The Problem:

You've got a JSON Schema with $ref pointers to other files and/or URLs. Maybe you know all the referenced files ahead of time. Maybe you don't. Maybe some are local files, and others are remote URLs. Maybe they are a mix of JSON and YAML format. Maybe some of the files contain cross-references to each other.

{
  "definitions": {
    "person": {
      // references an external file
      "$ref": "schemas/people/Bruce-Wayne.json"
    },
    "place": {
      // references a sub-schema in an external file
      "$ref": "schemas/places.yaml#/definitions/Gotham-City"
    },
    "thing": {
      // references a URL
      "$ref": "http://wayne-enterprises.com/things/batmobile"
    },
    "color": {
      // references a value in an external file via an internal reference
      "$ref": "#/definitions/thing/properties/colors/black-as-the-night"
    }
  }
}

The Solution:

JSON Schema $Ref Parser is a full JSON Reference and JSON Pointer implementation that crawls even the most complex JSON Schemas and gives you simple, straightforward JavaScript objects.

• Use JSON or YAML schemas — or even a mix of both!
• Supports $ref pointers to external files and URLs, as well as custom sources such as databases
• Can bundle multiple files into a single schema that only has internal $ref pointers
• Can dereference your schema, producing a plain-old JavaScript object that's easy to work with
• Supports circular references, nested references, back-references, and cross-references between files
• Maintains object reference equality — $ref pointers to the same value always resolve to the same object instance
• Compatible with Node LTS and beyond, and all major web browsers on Windows, Mac, and Linux

New in this fork (@hey-api)

• Multiple inputs with bundleMany: Merge and bundle several OpenAPI/JSON Schema inputs (files, URLs, or raw objects) into a single schema. Components are prefixed to avoid name collisions, paths are namespaced on conflict, and $refs are rewritten accordingly.

import { $RefParser } from '@hey-api/json-schema-ref-parser';

const parser = new $RefParser();
const merged = await parser.bundleMany({
  pathOrUrlOrSchemas: [
    './specs/a.yaml',
    'https://example.com/b.yaml',
    { openapi: '3.1.0', info: { title: 'Inline' }, paths: {} },
  ],
});

// merged.components.* will contain prefixed names like a_<name>, b_<name>, etc.

• Dereference hooks: Fine-tune dereferencing with excludedPathMatcher(path) => boolean to skip subpaths and onDereference(path, value, parent, parentPropName) to observe replacements.

const parser = new $RefParser();
parser.options.dereference.excludedPathMatcher = (p) => p.includes('/example/');
parser.options.dereference.onDereference = (p, v) => {
  // inspect p / v as needed
};
await parser.dereference({ pathOrUrlOrSchema: './openapi.yaml' });

• Smart input resolution: You can pass a file path, URL, or raw schema object. If a raw schema includes $id, it is used as the base URL for resolving relative $refs.

await new $RefParser().bundle({
  pathOrUrlOrSchema: {
    $id: 'https://api.example.com/openapi.json',
    openapi: '3.1.0',
    paths: {
      '/ping': { get: { responses: { 200: { description: 'ok' } } } },
    },
  },
});