npm install @hey-api/json-schema-ref-parser
pnpm add @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' } } } },
    },
  },
});